Colorant stabilizers

ABSTRACT

The present invention is directed to an ink set of inks which have substantially identical light fastness properties. The ink set includes ink compositions containing a colorant and at least one colorant stabilizer. The colorant stabilizer imparts light-stability to the colorant so that the colorant does not fade when exposed to electromagnetic radiation such as sunlight or artificial light. The ink set provides a range of colored inks having similar light-stability.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This patent application is a continuation-in-part patent application ofU.S. patent application Ser. No. 08/788,863 filed on Jan. 23, 1997,which is a continuation-in-part patent application of U.S. patentapplication Ser. No. 08/757,222 filed on Nov. 27, 1996, now U.S. Pat.No. 5,782,963, which is a continuation-in-part patent application ofU.S. patent application Ser. No. 08/627,693 filed on Mar. 29, 1996, nowabandoned both of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a family of colorant stabilizers. Thecolorant stabilizers, according to the present invention, are capable ofstabilizing a colorant when it is exposed to electromagnetic radiation.The colorant stabilizers enable the production of an ink set whereineach ink of the ink set, regardless of color, possesses substantiallysimilar light fastness properties.

BACKGROUND OF THE INVENTION

A major problem with colorants is that they tend to fade when exposed toelectromagnetic radiation such as sunlight or artificial light and thelike. It is believed that most of the fading of colorants when exposedto light is due to photodegradation mechanisms. These degradationmechanisms include oxidation or reduction of the colorants dependingupon the environmental conditions in which the colorant is placed.Fading of a colorant also depends upon the substrate upon which theyreside.

Product analysis of stable photoproducts and intermediates has revealedseveral important modes of photodecomposition. These include electronejection from the colorant, reaction with ground-state or excitedsinglet state oxygen, cleavage of the central carbon-phenyl ring bondsto form amino substituted benzophenones, such as triphenylmethane dyes,reduction to form the colorless leuco dyes and electron or hydrogen atomabstraction to form radical intermediates.

Various factors such as temperature, humidity, gaseous reactants,including O₂, O₃, SO₂, and NO₂, and water soluble, nonvolatilephotodegradation products have been shown to influence fading ofcolorants. The factors that effect colorant fading appear to exhibit acertain amount of interdependence. It is due to this complex behaviorthat observations for the fading of a particular colorant on aparticular substrate cannot be applied to colorants and substrates ingeneral.

Under conditions of constant temperature it has been observed that anincrease in the relative humidity of the atmosphere increases the fadingof a colorant for a variety of colorant-substrate systems (e.g.,McLaren, K., J. Soc. Dyers Colour, 1956, 72, 527). For example, as therelative humidity of the atmosphere increases, a fiber may swell becausethe moisture content of the fiber increases. This aids diffusion ofgaseous reactants through the substrate structure.

The ability of a light source to cause photochemical change in acolorant is also dependent upon the spectral distribution of the lightsource, in particular the proportion of radiation of wavelengths mosteffective in causing a change in the colorant and the quantum yield ofcolorant degradation as a function of wavelength. On the basis ofphotochemical principles, it would be expected that light of higherenergy (short wavelengths) would be more effective at causing fadingthan light of lower energy (long wavelengths). Studies have revealedthat this is not always the case. Over 100 colorants of differentclasses were studied and found that generally the most unstable werefaded more efficiently by visible light while those of higherlightfastness were degraded mainly by ultraviolet light (McLaren, K., J.Soc. Dyers Colour, 1956, 72, 86).

The influence of a substrate on colorant stability can be extremelyimportant. Colorant fading may be retarded or promoted by some chemicalgroup within the substrate. Such a group can be a ground-state speciesor an excited-state species. The porosity of the substrate is also animportant factor in colorant stability. A high porosity can promotefading of a colorant by facilitating penetration of moisture and gaseousreactants into the substrate. A substrate may also act as a protectiveagent by screening the colorant from light of wavelengths capable ofcausing degradation.

The purity of the substrate is also an important consideration wheneverthe photochemistry of dyed technical polymers is considered. Forexample, technical-grade cotton, viscose rayon, polyethylene,polypropylene, and polyisoprene are known to contain carbonyl groupimpurities. These impurities absorb light of wavelengths greater than300 nm, which are present in sunlight, and so, excitation of theseimpurities may lead to reactive species capable of causing colorantfading (van Beek, H.C.A., Col. Res. Appl., 1983, 8(3), 176).

Therefore, there exists a need for methods and compositions which arecapable of stabilizing a wide variety of colorants from the effects ofboth sunlight and artificial light.

SUMMARY OF THE INVENTION

The present invention addresses the needs described above by providingcompositions and methods for stabilizing colorants against radiationincluding radiation in the visible wavelength range.

The present invention also relates to colorant compositions havingimproved stability, wherein the colorant is associated with a colorantstabilizer. In one embodiment, the colorant stabilizer of the presentinvention is an aryliminealkene having the following general formula:##STR1## wherein R₁ is hydrogen, an alkyl, alkenyl, cycloalkyl,heterocycloalkyl, aryl, heteroaryl group, or substituted aryl group;

R₂ is hydrogen, an alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl,heteroaryl group, or substituted aryl group;

R₃ is hydrogen, an alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl,heteroaryl group, or substituted aryl group;

R₄ is hydrogen, an alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl,heteroaryl, or substituted aryl group; and

R₅ is an aryl, heteroaryl, polyalkene, or substituted aryl group;

wherein R₁, R₂, or R₄ is an aryl, heteroaryl, or substituted aryl group.

Desirably, the alkene group is in the trans configuration.

In another embodiment of the present invention, heavy atoms are added toconventional dyes to stabilize the dyes. These heavy atoms include GroupVII ions including iodide ions. It has further been determined that thecounterion is desirably a large ion with a relatively low chargedensity. These counterions should be sodium or larger. The counterionsalso include relatively large organic counterions such astetramethylammonium.

In yet another embodiment of the present invention, highly effective dyestabilizers include derivatives of phenols with the following generalformula: ##STR2## wherein R₁ is iodine, or an alkyl group having between1 and 5 carbon atoms;

R₂ is an iodine, or an alkyl group having between 1 and 5 carbon atoms;

R₃ is iodine, or an alkyl group having between 1 and 5 carbon atoms; and

R₄ is a sugar, polyhydroxy compound, sulfonic acid salt compound,carboxylic acid salt compound, polyether compound, or hydrogen, whereinthe sugar includes, but is not limited to, glucose, fructose, polyethersugars, monosaccharides, polysaccharides, cyclodextrins, including butnot limited to, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin,hydroxypropyl β-cyclodextrin, hydroxyethyl β-cyclodextrin, hydroxyethylα cyclodextrin, carboxymethyl α cyclodextrin, carboxymethyl βcyclodextrin, carboxymethyl γ cyclodextrin, octyl succinated αcyclodextrin, octyl succinated β cyclodextrin, octyl succinated γcyclodextrin and sulfated β cyclodextrin and sulfated γ-cyclodextrin. Inparticular, the triiodophenols and trimethylphenols and the watersoluble derivatives thereof are particularly effective in stabilizing awide variety of dyes.

In yet another embodiment, the colorant stabilizer of the presentinvention is a reducing agent. The reducing agent includes, but is notlimited to, sodium thiosulfate (Na₂ S₂ O₃), sodium sulfite (Na₂ SO₃),cysteine, sodium nitrite, sodium phosphite, and citric acid. A desiredreducing agent is sodium thiosulfate. In this embodiment, the stabilizermay be admixed with the colorant, or it may be applied to a substrate towhich the colorant will be applied. Although the reducing agent alonestabilizes a colorant, it is desirable that the reducing agent iscombined with one or more of the above stabilizers.

In another embodiment, the colorant stabilizer of the present inventionis a molecular includant having a chemical structure which defines atleast one cavity. The molecular includant may be on or in a substrate towhich the colorant will be applied, or it may be present in a colorantsolution. The molecular includant may be, but is not limited to,clathrates, zeolites, crown ethers, calixarenes, valinomycin typenatural antibiotics, various polyether compounds, nigericin type naturalantibiotics, and cyclic compounds containing a plurality of pyranoserings. The cyclic compounds include, but are not limited to,cyclodextrins such as α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin,δ-cyclodextrin, and derivatives thereof. A desired molecular includantis cyclodextrin. A more desired molecular includant is γ-cyclodextrin.Desirably, the molecular includant is present on or in the substrate towhich the colorant will be applied.

The substrates to which the colorant stabilizers are applied include,but are not limited to, paper, wood, a wood product or composite, wovenfabric, nonwoven fabric, textile, plastic, glass, metal, or any othersubstrate that would benefit from having a stabilized colorant thereon.

Although the molecular includant in or on the substrate stabilizes acolorant that is applied thereto, it is desirable that the colorant iscombined with one or more of the above stabilizers. Additionally, in theembodiment where the molecular includant is present in a colorantsolution, the colorant stabilizing molecules can be associated with oneor more molecular includants. Additionally, the includants can havemultiple colorant stabilizing molecules associated therewith. In someembodiments, the colorant is at least partially included within a cavityof the molecular includant and the colorant stabilizing molecules areassociated with the molecular includant outside of the cavity. In someembodiments, the colorant stabilizing molecules are covalently coupledto the outside of the molecular includant.

In another embodiment, a colorant stabilizer, such as a molecularincludant, is present in a polymer coating of a heat transfer product,such as is used for transferring graphic images onto clothing.

In another embodiment, a colorant stabilizer comprises one or moreporphines that have an extremely short triplet state lifetime. (Seee.g., Kubat, et al., Photophysical properties of metal complexes ofmeso-tetrakis (4-sulphonatophenyl) porphyrin, J. Photochem. and Photbio.A: Chemistry 96 (1996), pgs 93-97 which is incorporated herein byreference). Particularly suitable porphines include, but are not limitedto, porphines having the following structure: ##STR3## wherein R is anyproton-donating moiety and M is cobalt or copper. Desirably, R is SO₃ H,##STR4## COOH, or R₁ COOH wherein R₁ is an alkyl group of from 1 to 6carbons.

Examples of such porphines areCu-meso-tetra-(4-sulfanatophenyl)-porphine (designated CuTPPS4) andCu-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures: ##STR5## wherein the copper ion can also be substituted witha cobalt ion. Other metal ions, such as an iron ion, can be substitutedin the porphine molecule as long as the molecule has a relativelyshort-lived triplet state.

In a further embodiment, the colorant stabilizer comprises at least onemetal or metal salt, alone or in combination with, at least one othercolorant stabilizer of the present invention. Desirably, the metal ormetal salt is used in combination with at least one other colorantstabilizer, such as a porphine or a benzophenone. Unexpectedly, it hasbeen discovered that the incorporation of a relatively smallconcentration of metal or metal salt into a porphine-containingcomposition results in superior colorant stability. Preferred metals ormetal salts include, but are not limited to, lanthanides and lanthanidesalts. Lanthanide elements include scandium, yttium, lanthanum, ceriumpraseodymium, neodymium, promethium, samarium, europium, gadolinium,terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.Other suitable metal and metal salts include magnesium, iron, zinc,other transition metals, and heavy metals.

In order to improve the solubility of the metal or metal salt insolution, metal solubility-enhancing agents may be added. Particularlyuseful metal solubility-enhancing agents include, but are not limitedto, chelating agents. Optionally, a surfactant can be added to themetal/porphine composition to increase the interaction of the metal ormetal salt and the porphine. In addition to surfactants, other additivessuch as TINUVIN® compounds (Ciba-Geigy Corporation) may be incorporatedinto the colorant composition.

The colorant stabilizing additive can also optionally be dimethyl aminobenzoic acid quat (designated DMABAQ), represented by the followingstructure: ##STR6## The colorant stabilizing additive can alsooptionally be a basic fuschin hydrazone, represented by the followingstructure: ##STR7##

In addition, the colorant stabilizing additive of this invention is abenzophenone, of the general formula: ##STR8## wherein R represents anysubstituents which permit the benzophenone to function as a colorantstabilizer.

Accordingly, each of these embodiments of the present invention providestabilizing molecules that, when one or more of the stabilizingmolecules are associated with a colorant, stabilizes the colorant.Therefore, the stabilizing molecules can be used as an additive to anycolorant composition. For example, as certain of the stabilizingmolecules are poorly soluble in water, they can be directly added tosolvent or oil based (not water based) colorant compositions.Additionally, the stabilizing molecules can be added to other colorantcompositions that contain additives enabling the solubilization of thestabilizing molecule therein. Further, the stabilizing molecules can besolubilized in an aqueous solution by attaching the molecule to a largewater soluble molecule, such as a cyclodextrin.

The colorant stabilizers are particularly effective in ink jet inks. Useof the colorant stabilizers, as described herein, intensifies the colorsand stabilizes the colors when exposed to light. Additionally, thecolorant stabilizers are particularly effective in paper such as ink jetpaper. Use of the colorant stabilizers in a substrate, as describedherein, stabilizes a colorant to which it is applied. Also, colorantstabilizers in a substrate has been found to have the unexpected resultof reducing the yellowing of the substrate itself upon exposure tolight.

The colorant stabilizers are of particular interest in the formation ofink sets, wherein each ink of the ink set, regardless of color,possesses substantially identical light fastness properties as the otherinks in the ink set. The ink set enables the production of multi-colortext and/or graphics, which uniformly retain their color over extendedperiods of time and/or upon extended exposure to light.

These and other features and advantages of the present invention willbecome apparent after a review of the following detailed description ofthe disclosed embodiments and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

This application is directed to compositions and methods for stabilizingcolorants against radiation including radiation in the visiblewavelength range. This application is further directed to ink setscomprising four or more inks, each of which possesses substantiallyidentical light stability upon exposure to radiation, includingradiation in the visible wavelength range. The compositions and methodsrelating to stabilizing a colorant by admixing a stabilizing moleculewith a colorant solution will first be addressed below. Subsequently,the compositions and methods relating to stabilizing a colorant byapplying the colorant to a treated substrate containing a stabilizingmolecule will be discussed.

Admixing Stabilizing Molecules Into Colorant Solutions.

The present invention relates to colorant compositions having improvedstability, wherein the colorant stabilizer is associated with a colorantsolution. Desirably, the colorant stabilizer is admixed with a colorantsolution. The colorant stabilizer is desirably an aryliminealkenecompound. Other desired colorant stabilizers are heavy atoms such as theiodide ion, phenol derivatives such as triiodophenol, trimethylphenol,and metals or metal salts, and derivatives thereof. Additional colorantstabilizers include reducing agents such as sodium thiosulfate.Furthermore, colorant stabilizers include porphines alone or incombination with at least one metal or metal salt; hydrazones;benzophenones; and combinations of one or more of the above colorantstabilizers. The colorant stabilizers of the present invention areadmixed with a colorant to stabilize the colorant when the admixture isexposed to electromagnetic radiation such as artificial light orsunlight.

The present invention further relates to a method of stabilizing acolorant comprising associating one or more of the colorant stabilizerswith the colorant solution. Optionally, the colorant stabilizer may beassociated with a molecular includant, chelating agent, or othermaterial to improve solubility and/or interaction of the colorantstabilizer and the colorant.

The present invention is particularly useful for stabilizing inks to beused in ink jet printers. Inks used in ink jet printers are described inU.S. patent application Ser. No. 08/769,885 filed on Dec. 19, 1996,which is a continuation of U.S. patent application Ser. No. 08/461,382filed on Jun. 5, 1995, now abandoned, which is a divisional of U.S.patent application No. 08/461,365 filed on Jun. 5, 1995, now abandoned,all of which are incorporated herein by reference.

Thus, in one embodiment, the aryliminealkene stabilizing composition isshown by the following general formula: ##STR9## wherein R₁ is hydrogen,an alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl group,or substituted aryl group;

R₂ is hydrogen, an alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl,heteroaryl group, or substituted aryl group;

R₃ is hydrogen, an alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl,heteroaryl group, or substituted aryl group;

R₄ is hydrogen, an alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl,heteroaryl, or substituted aryl group; and

R₅ is an aryl, heteroaryl, or substituted aryl group;

wherein R₁, R₂, or R₄ is an aryl, heteroaryl, or substituted aryl group.

Desirably, the alkene group is in the trans configuration.

Desirably, the aryliminealkene stabilizing compound has one of thefollowing formulae: ##STR10##

Accordingly, this embodiment of the present invention provides astabilizing molecule, the above aryliminealkene, which when associatedwith a colorant, stabilizes the colorant. Therefore, the abovearyliminealkene can be used as an additive to any colorant composition.For example, as certain of the aryliminealkene compounds are poorlywater soluble, they can be directly added to solvent or oil based (notwater based) colorant compositions. Additionally, the aryliminealkenecompound can be added to other colorant compositions that containadditives enabling the solubilization of the compound therein. Further,the aryliminealkene stabilizing compounds can be solubilized in anaqueous solution by associating the compound with a large water solublemolecule, such as a cyclodextrin.

The term "composition" and such variations as "colored composition" areused herein to mean a colorant and one or more colorant stabilizers ofthe present invention. The composition can optionally include molecularincludant.

As used herein, the term "colorant" is meant to include, withoutlimitation, any material which typically will be an organic material,such as an organic colorant or dye. The term is meant to include asingle material or a mixture of two or more materials.

The term "light-stable" is used herein to mean that the colorant, whenassociated with one of the colorant stabilizing molecules of the presentinvention, is more stable to electromagnetic radiation, including, butnot limited to, sunlight or artificial light, than when the colorant isnot associated with such a compound.

The term "molecular includant," as used herein, is intended to mean anysubstance having a chemical structure which defines at least one cavity.That is, the molecular includant is a cavity-containing structure. Asused herein, the term "cavity" is meant to include any opening or spaceof a size sufficient to accept at least a portion of the colorant.

The term "functionalized molecular includant" is used herein to mean amolecular includant to which one or more molecules of a colorantstabilizer are covalently coupled to each molecule of the molecularincludant. The term "degree of substitution" is used herein to refer tothe number of these molecules or leaving groups (defined below) whichare covalently coupled to each molecule of the molecular includant.

The term "derivatized molecular includant" is used herein to mean amolecular includant having more than two leaving groups covalentlycoupled to each molecule of molecular includant. The term "leavinggroup" is used herein to mean any leaving group capable of participatingin a bimolecular nucleophilic substitution reaction. Examples ofmolecular includants include, but are not limited to, the cyclodextrins.

The term "artificial light" is used herein to mean light having arelatively broad bandwidth that is produced from conventional lightsources, including, but not limited to, conventional incandescent lightbulbs and fluorescent light bulbs.

The term "thereon" is used herein to mean thereon or therein. Forexample, the present invention includes a substrate having a coloredcomposition thereon. According to the definition of "thereon" thecolored composition may be present on the substrate or it may be in thesubstrate.

In several embodiments, the colorant stabilizer may be optionallyassociated with a molecular includant. It is to be noted that in all thecompositions that contain a molecular includant, the number of suchstabilizer molecules can be between approximately 1 and approximately 21molecules per molecular includant. Of course, in certain situations,there can be more than 21 molecules per molecular includant molecule.Desirably, there are more than three of such stabilizer molecules permolecular includant.

The degree of substitution of the functionalized molecular includant maybe in a range of from 1 to approximately 21. As another example, thedegree of substitution may be in a range of from 3 to about 10. As afurther example, the degree of substitution may be in a range of fromabout 4 to about 9.

In some embodiments of the present invention, the colorant is associatedwith the molecular includant. The term "associated" in its broadestsense means that the colorant is at least in close proximity to themolecular includant. For example, the colorant may be maintained inclose proximity to the molecular includant by hydrogen bonding, van derWaals forces, or the like. Alternatively, the colorant may be covalentlybonded to the molecular includant, although this normally is neitherdesired nor necessary. As a further example, the colorant may be atleast partially included within the cavity of the molecular includant.

The dye or colorant, for example, may be an organic dye. Organic dyeclasses include, by way of illustration only, triarylmethyl dyes, suchas Malachite Green Carbinol base {4-(dimethylamino)-α-4-(dimethylamino)phenyl!-α-phenyl-benzene-methanol}, Malachite GreenCarbinol hydrochloride {N-4-4-(dimethylamino)phenyl!phenyl-methylene!-2,5-cyclohexyldien-1-ylidene!-N-methyl-methanaminiumchloride or bis p-(dimethylamino)phenyl!phenylmethylium chloride}, andMalachite Green oxalate {N-4-4-(dimethylamino)-phenyl!-phenyhnethylene!-2,5-cyclohexyldien-1-ylidene!-N-methyl-methanaminiumchloride or bis p-(dimethylamino)-phenyl!phenylmethylium oxalate};monoazo dyes, such as Cyanine Black, Chrysoidine Basic Orange 2;4-(phenylazo)-1,3-benzenediamine monohydrochloride!, Victoria Pure BlueBO, Victoria Pure Blue B, basic fuschin and β-Naphthol Orange; thiazinedyes, such as Methylene Green, zinc chloride double salt3,7-bis(dimethylamino)-6-nitrophenothiazin-5-ium chloride, zinc chloridedouble salt!; oxazine dyes, such as Lumichrome (7,8-dimethylalloxazine);naphthalimide dyes, such as Lucifer Yellow CH {6-amino-2-(hydrazino-carbonyl)amino!-2,3-dihydro- 1,3-dioxo-1H-benzde!iso-quinoline-5,8-disulfonic acid dilithium salt}; azine dyes, suchas Janus Green B {3-(diethylamino)-7-4-(dimethyl-amino)phenyl!azo!-5-phenylphenazinium chloride}; cyaninedyes, such as Indocyanine Green {Cardio-Green or Fox Green; 2- 7-1,3-dihydro-1,1-dimethyl-3-(4-sulfobutyl)-2H-benze!indol-2-ylidene!-1,3,5-heptatrienyl!-1,1-dimethyl-3-(4-sulfobutyl)-1H-benze!indolium hydroxide inner salt sodium salt}; indigo dyes, such asIndigo {Indigo Blue or Vat Blue 1;2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one};coumarin dyes, such as 7-hydroxy-4-methyl-coumarin(4-methylumbelliferone); benzimidazole dyes, such as Hoechst 33258bisbenzimide or2-(4-hydroxyphenyl)-5-(4-methyl-1-piperazinyl)-2,5-bi-1H-benzimidazoletrihydro-chloride pentahydrate!; paraquinoidal dyes, such as Hematoxylin{Natural Black 1; 7,11b-dihydrobenz b!-indeno1,2-d!pyran-3,4,6a,9,10(6H)-pentol}; fluorescein dyes, such asFluoresceinamine (5-aminofluorescein); diazonium salt dyes, such asDiazo Red RC (Azoic Diazo No. 10 or Fast Red RC salt;2-methoxy-5-chlorobenzenediazonium chloride, zinc chloride double salt);azoic diazo dyes, such as Fast Blue BB salt (Azoic Diazo No. 20;4-benzoylamino-2,5-diethoxy-benzene diazonium chloride, zinc chloridedouble salt); phenylenediamine dyes, such as Disperse Yellow 9N-(2,4-dinitrophenyl)-1,4-phenylenediamine or Solvent Orange 53!; diazodyes, such as Disperse Orange 13 Solvent Orange 52; 1-phenylazo-4-(4-hydroxyphenylazo)naphthalene!; anthra-quinone dyes, such as DisperseBlue 3 Celliton Fast Blue FFR;1-methylamino-4-(2-hydroxyethylamino)-9,10-anthraquinone!, Disperse Blue14 Celliton Fast Blue B; 1,4-bis(methylamino)-9,10-anthraquinone!, andAlizarin Blue Black B (Mordant Black 13); trisazo dyes, such as DirectBlue 71 {Benzo Light Blue FFL or Sirius Light Blue BRR; 3- (4- (4-(6-amino-1-hydroxy-3-sulfo-2-naphthalenyl)azo!-6-sulfo-1-naphthalenyl)-azo!-1-naphthalenyl)azo!-1,5-naphthalenedisulfonicacid tetrasodium salt}; xanthene dyes, such as 2,7-dichloro-fluorescein;proflavine dyes, such as 3,6-diaminoacridine hemisulfate (Proflavine);sulfonaphthalein dyes, such as Cresol Red (o-cresolsulfonaphthalein);phthalocyanine dyes, such as Copper Phthalocyanine {Pigment Blue 15;(SP-4-1)- 29H,31H-phthalocyanato(2-)-N²⁹,N³⁰,N³¹,N³² !copper};carotenoid dyes, such as trans-β-carotene (Food Orange 5); carminic aciddyes, such as Carmine, the aluminum or calcium-aluminum lake of carminicacid(7-a-D-glucopyranosyl-9,10-dihydro-3,5,6,8-tetrahydroxy-1-methyl-9,10-dioxo-2-anthracene-carbonylicacid); azure dyes, such as Azure A3-amino-7-(dimethylamino)phenothiazin-5-ium chloride or7-(dimethyl-amino)-3-imino-3H-phenothiazine hydrochloride!; and acridinedyes, such as Acridine Orange Basic Orange 14;3,8-bis(dimethylamino)acridine hydrochloride, zinc chloride double salt!and Acriflavine (Acriflavine neutral; 3,6-diamino-10-methylacridiniumchloride mixture with 3,6-acridine-diamine).

In preparing the aryliminealkene colorant stabilizer of the presentinvention, one can, for example, start with a chalcone which isrepresented by the following formula: ##STR11##

It is to be understood that the phenyl groups on the chalcone can besubstituted with a wide variety of substituents. The chalcone is thenreacted with a primary amine having the following general formula:

    NH.sub.2 --R

wherein R is an aryl, heteroaryl, or substituted aryl group. A desirableprimary amine is 2 amino benzene sulfonic acid. The reaction is carriedout in a nonaqueous solvent such as absolute alcohol. The resultingcompound has the following general structure: ##STR12##

Accordingly, one colorant stabilizer of the present invention is anaryliminealkene having the following general formula: ##STR13## whereinif R₁ is an aryl group, then R₂ is a hydrogen; heterocyclic; alkyl;aryl, or a phenyl group, the phenyl group optionally being substitutedwith an alkyl, halo, amino, or a thiol group; and if R₂ is an arylgroup, then R₁ is hydrogen; heterocyclic; alkyl; aryl, or a phenylgroup, the phenyl group optionally being substituted with an alkyl,halo, amino, or a thiol group. R₃ is an aryl, heteroaryl, or substitutedaryl group. Desirably, the alkene group is in the trans configuration.

Desirably, the aryliminealkene stabilizing compound has one of thefollowing formulae: ##STR14##

The SO₃ H group can be in the ortho, meta or para position.

Yet another aryliminealkene compound is an imine adduct of basic fuschinand is shown in the following formula: ##STR15## The imine adduct ofbasic fuschin can be synthesized according to Example 7 below.

In the embodiment where the aryliminealkene compound is covalentlyattached to another molecule, whichever R₁ or R₂ that is an aryl groupwill have a group including, but not limited to, a carboxylic acidgroup, an aldehyde group, an amino group, a haloalkyl group, a hydroxylgroup, or a thioalkyl group attached thereto to allow thearyliminealkene to be covalently bonded to the other molecule.Accordingly, the aryliminealkene stabilizing compound is represented byone of the following formulae: ##STR16## wherein R is an aryl,heteroaryl, or substituted aryl group. Although it is preferred that thegroup attached to the aryl group is para to the remainder of thestabilizer molecule, the group may also be ortho or meta to theremainder of the molecule.

Accordingly, this embodiment of the present invention provides astabilizing aryliminealkene which, when associated with a colorant,stabilizes the colorant. Therefore, the above aryliminealkenes can beused as an additive to any colorant composition. For example, if thearyliminealkene compound is not water soluble or is poorly watersoluble, it can be directly added to solvent or oil colorantcompositions. Additionally, the aryliminealkene compound can be added toother colorant compositions that contain additives enabling thesolubilization of the compound therein.

This embodiment provides a method for stabilizing a colorant by admixingthe aryliminealkene compound with the colorants in an amount effectiveto stabilize the colorant. The aryliminealkene desirably should bepresent in the colorant solution at a concentration of approximately 0.1to 50% by weight, desirably between approximately 20% and 30% by weight.In other words, the aryliminealkene should be equivalent inconcentration to the colorant or should be at a higher concentrationthan the colorant. If no cyclodextrin or derivatized cyclodextrin isused, the desirable range is approximately 1 part dye to approximately20 parts aryliminealkene.

Although the aryliminealkene compound need only be associated with thecolorant, in some embodiments of the present invention, thearyliminealkene compound may be covalently bonded to the colorant.

Another embodiment of the present invention is amino sulfonic acidrepresented by the following formula: ##STR17##

The SO₃ H group can be in the ortho, meta or para position.

Another embodiment of colorant stabilizers include derivatives ofphenols with the following general formula: ##STR18## wherein R₁ isiodine, or an alkyl group having between 1 and 5 carbon atoms;

R₂ is an iodine, or an alkyl group having between 1 and 5 carbon atoms;

R₃ is iodine, or an alkyl group having between 1 and 5 carbon atoms; and

R₄ is a hydrogen, sugar, polyhydroxy compound, sulfonic acid saltcompound, carboxylic acid salt compound, polyether compound, orhydrogen, wherein the sugar includes, but is not limited to, glucose,fructose, polyether sugars, monosaccharides, polysaccharides,cyclodextrins, including but not limited to, α-cyclodextrin,β-cyclodextrin, γ-cyclodextrin, hydroxypropyl β-cyclodextrin,hydroxyethyl β-cyclodextrin, hydroxyethyl α cyclodextrin, carboxymethylα cyclodextrin, carboxymethyl β cyclodextrin, carboxymethyl γcyclodextrin, octyl succinated α cyclodextrin, octyl succinated βcyclodextrin, octyl succinated γ cyclodextrin and sulfated βcyclodextrin and sulfated γ-cyclodextrin.

The phenol derivatives are desirably added to the colorant solution at aconcentration of between 0.5 and 10 molar equivalents to theconcentration of the colorant.

A desired colorant stabilizer is triiodophenol (Aldrich). Thetriiodophenol has the following formula: ##STR19## The triiodophenolatesare desirably added to the colorant solution at a concentration ofbetween 0.5 and 10 equivalents to the concentration of the colorant.

A desired colorant stabilizer includes trimethylphenol and derivativesthereof. The trimethylphenols have the following formula, wherein one ormore of the methyl groups may be substituted with another alkyl oralkenyl group: ##STR20## The trimethylphenols are desirably added to thecolorant solution at a concentration of between 0.5 and 10 equivalentsto the concentration of the colorant. Similarly, another desiredcolorant stabilizer is triiodophenol, which is desirably added to thecolorant solution at a concentration of between 0.5 and 10 equivalentsto the concentration of the colorant.

Further, the water solubility of the stabilizing compounds, includingbut not limited to the aryliminealkenes or triiodophenols or thetrimethyphenols, can be increased by a variety of means. The desirablemeans of increasing the water solubility of the phenol-based stabilizingcompounds is to add a water soluble moiety to the hydroxyl group on thephenol. In this embodiment, R₄ of the above phenol figure is a sugar,polyhydroxy compound, sulfonic acid salt compound, carboxylic acid saltcompound, or polyether compound, wherein the sugar includes, but is notlimited to, glucose, fructose, polyether sugars, monosaccharides,polysaccharides, cyclodextrins, including but not limited to,α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, hydroxypropylβ-cyclodextrin, hydroxyethyl β-cyclodextrin, hydroxyethyl αcyclodextrin, carboxymethyl α cyclodextrin, carboxymethyl βcyclodextrin, carboxymethyl γ cyclodextrin, octyl succinated αcyclodextrin, octyl succinated β cyclodextrin, octyl succinated γcyclodextrin and sulfated β cyclodextrin and sulfated γ-cyclodextrin.

Accordingly, in one embodiment of the present invention the means ofincreasing the water solubility of the stabilizing compounds of thepresent invention is to react the phenol with a sugar, to produce thefollowing representative compounds: ##STR21## wherein R is any groupcapable of rendering the phenol more water soluble. More particularly,the R group may be, but is not limited to a sugar, polyhydroxy compound,sulfonic acid salt compound, carboxylic acid salt compound, or polyethercompound, wherein the sugar includes, but is not limited to, glucose,fructose, polyether sugars, monosaccharides, polysaccharides,cyclodextrins, including but not limited to, α-cyclodextrin,β-cyclodextrin, γ-cyclodextrin, hydroxypropyl β-cyclodextrin,hydroxyethyl β-cyclodextrin, hydroxyethyl α cyclodextrin, carboxymethylα cyclodextrin, carboxymethyl β cyclodextrin, carboxymethyl γcyclodextrin, octyl succinated α cyclodextrin, octyl succinated βcyclodextrin, octyl succinated γ cyclodextrin and sulfated βcyclodextrin and sulfated γ-cyclodextrin. A desired R group is1,2-o-isopropylidene-D-glucofuranose. The resultant desiredstabilization compound is represented by one of the following formulae:##STR22##

Examples 21, 22 and 24 describe how to prepare the above water solublephenols. A more desired R group is glucose, where the ketal group of theabove phenol-sugar compounds has been removed as described in Examples23 and 25 producing the stabilizing compounds shown below: ##STR23##

The colorant stabilizer compounds above in which the ketal group hasbeen removed is a more desired stabilizer compound as it is more watersoluble than if the ketal group is present.

Another desired colorant stabilizing compound is3-(2,4,6-triiodophenoxy)-1,2-propanediol, as shown below: ##STR24##

Another means of increasing the water solubility of the stabilizingcompounds of the present invention is to associate the compound to alarge water soluble molecule, such as a cyclodextrin or desirably aderivatized cyclodextrin. Desirably, the derivatized cyclodextrin isethylhydroxy β-cyclodextrin. An example of such a covalent associationof the stabilizing compounds is the triiodophenol or the trimethylphenolcovalently bound with an ethylhydroxy β-cyclodextrin as represented inthe following formulae: ##STR25## wherein n=1 to 21 and CD=cyclodextrin.The aryliminealkenes can be covalently attached to the β-cyclodextrinvia any suitable functional group. An example of such an association isrepresented in the following formula: ##STR26## wherein R is an aryl,heteroaryl, or substituted aryl group, n=1 to 21 and CD=β-cyclodextrin.It is to be understood that any of the aryliminealkenes can becovalently attached to the derivatized cyclodextrin through theappropriate functional groups. The water solubility of thetriiodophenols or the trimethyphenols can be increased by adding asoluble compound to the molecule.

The association can be an admixture or can be a covalent attachment.Desirably, between about 1 and 12 stabilizing molecules can be attachedto a cyclodextrin molecule. More desirably, between about 4 to about 9stabilizing molecules are attached to a cyclodextrin molecule.Accordingly, the stabilizing compound attached to cyclodextrin can beadded to any aqueous colorant system to stabilize the colorant therein.It is to be understood that the stabilizing aryliminealkenes do not haveto be attached to the molecular includants to exhibit their stabilizingactivity.

Although not wanting to be limited by the following, it is thought thatthe stabilizer compounds of the present invention exhibit excellentstabilizing properties as their high water solubility maintains theamount of additive present in solution over time, so that the additivecontinues to provide its stabilization properties to the admixture. Astabilizing additive precipitating out of a colorant compositionnegatively impacts the composition as less of the stabilizer remains inthe solution, and therefore the colorant composition is less stabilized.Further, if the stabilizing additive is used in ink jet inks andcartridges, such precipitation can clog the ink jet printer and canother wise negatively impact the printing quality of the ink. Asurprising and unexpected feature of the present invention is that thestabilizing compound is extremely water soluble, and does notprecipitate out of ink solutions over time.

A third class of colorant stabilizers that are considered part of thepresent invention are heavy atoms such as iodide, xenon, andlanthanides. These compounds are desirably associated with largecounterions such as sodium or larger counterions such as nitrates. Ithas been determined that smaller counterions, such as potassium, providepoor stabilization of the colorants. The desirable salt is sodiumiodide. Another desirable salt is tetramethyl ammonium iodide. A furtherdesirable salt is europium nitrate. The preferred concentration of theheavy atoms is between approximately 0.5 to 5 mole equivalents. Theheavy atom salt is added to the colorant before exposure to theelectromagnetic radiation.

Examples 26 and 27 report the fade testing results of Hewlett Packardmagenta ink admixed with various combinations of stabilizing compoundsof the present invention. More particularly, 3 molar equivalents of thetrimethylphenol sugar produced in Example 23, 4 molar equivalents of thetriiodophenol sugar produced in Example 25, and two molar equivalents ofsodium iodide were admixed with HP magenta ink having already admixedtherein 2% by weight β-hydroxyethyl cyclodextrin. It is to be understoodthat the molar equivalents of the various stabilizing compounds can bevaried. In comparison with the ink on the control sheets of paper andtransparencies, the above described ink on paper and transparencies wasmuch more stable. (See the tables in Example 26, and Example 27).

It is desirable that a colorant solution be stabilized with one or moreof the following components in the following amounts: 2 to 10% wt/wtcyclodextrin or derivative thereof; 4-6% wt/wt of an aryliminealkenestabilizer of the present invention; 0.25 to 2 molar equivalents (eq) ofan iodide; 2 to 7 eq of a triiodophenol sugar; 2 to 7 eq of a trialkylphenol sugar; and 2 to 3 eq of ascorbic acid. More desirably, thecolorant solution is to be stabilized with 2 to 10% wt/wt hydroxyethylcyclodextrin; 4-6% wt/wt of an aryliminealkene stabilizer of the presentinvention; 0.25 to 2 molar equivalents (eq) of sodium iodide ortetramethyl amine iodide; 2 to 7 eq of a triiodophenol sugar; 2 to 7 eqof a trimethyl phenol sugar; and 2 to 3 eq of ascorbic acid. It is to beunderstood that units of "eq" or "molar equivalents" for stabilizingadditives refers to molar equivalents of the stabilizing additives withrespect to the dye. Additionally, it is to be understood that units of"wt/wt" for stabilizing additives refers to the weight of the additivewith respect to the weight of the ink or colorant solution.

In another embodiment, a colorant solution is stabilized with thefollowing: 4-10% fuschin imine adduct (Example 7); 0.25 to 2 eq of aniodide ion; and 2-10% β-cyclodextrin, desirably hydroxyethylβ-cyclodextrin.

In another embodiment described in Example 37, a colorant stabilizer,such as a molecular includant, is present in a polymer coating of a heattransfer product, such as is used for transferring graphic images ontoclothing.

In another embodiment of the present invention, a colorant stabilizer isrepresented by porphines having an extremely short triplet statelifetime. (See e.g., Kubat, et al., Photophysical properties of metalcomplexes of meso-tetrakis (4-sulphonatophenyl) porphyrin, J. Photochem.and Photbio. A: Chemistry 96 (1996), pgs 93-97 which is incorporatedherein by reference). Particularly suitable porphines include, but arenot limited to, porphines having the following structure: ##STR27##wherein R is any proton-donating moiety and M is cobalt or copper.Desirably, R is SO₃ H, ##STR28## COOH, or R₁ COOH wherein R₁ is an alkylgroup of from 1 to 6 carbons.

Desirably, the colorant stabilizer is represented by the porphinesCu-meso-tetra-(4-sulfanatophenyl)-porphine (designated CuTPPS4) andCu-meso-tetra-(N-methyl-4-pyridyl)-porphine (designated CuTMPS4), havingthe following structure: ##STR29## wherein the copper ion can also besubstituted with a cobalt ion. It is also understood that in the case ofCuTPPS4 or CoTPPS4, the sulfuric acid moieties may be substituted withsalts when in solution, such as sodium salts. The colorant solution maybe stabilized with about 0.1% to 10% wt/wt porphine, more preferablyabout 0.3% to 1% wt/wt porphine, and more preferably about 0.5% wt/wtporphine.

The above porphines are used as colorant stabilizers in colorantcompositions described in Example 38. In another embodiment described inExample 38, the colorant stabilizing additive can also optionally bedimethyl amino benzoic acid quat (designated DMABAQ), represented by thefollowing structure: ##STR30##

The colorant solution may be stabilized with about 0.1% to 15% wt/wtDMABAQ, more preferably about 0.5% to 10% wt/wt DMABAQ, and morepreferably about 1% to 5% wt/wt DMABAQ.

In another embodiment, the colorant stabilizer comprises a metal ormetal salt, such as magnesium and magnesium salt, alone or incombination with, other colorant stabilizers. Desirably, the amount ofmetal or metal salt in the colorant solution is from about 0.01% to 10%wt/wt metal, more desirably about 0.03% to 1% wt/wt metal, and moredesirably about 0.05% wt/wt metal. Although lanthanides and lanthanidesalts are desired metals, other metals, may also be used such asmagnesium, iron, zinc, and other transition metals. To improve thesolubility of the metal or metal salt in solution, metalsolubility-enhancing agents may be added. Particularly useful metalsolubility-enhancing agents include, but are not limited to, chelatingagents, including, but not limited to, EDTA (ethylenediaminetetraaceticacid) or EGTA (ethylene glycol-bis(β-aminoethyl ether)).

In a further embodiment, the colorant stabilizer comprises a porphineand a lanthanide, such as europium. Desirably, the amount of porphine inthe colorant solution is from about 0.1% to 10% wt/wt porphine, moredesirably about 0.3% to 1% wt/wt porphine, and more desirably about 0.5%wt/wt porphine. Desirably, the amount of lanthanide in the colorantsolution is from about 0.01% to 10% wt/wt lanthanide, more desirablyabout 0.03% to 1% wt/wt lanthanide, and more desirably about 0.05% wt/wtlanthanide. Although europium and europium salts are desiredlanthanides, other lanthanides, may also be used.

In another embodiment described in Example 40, the colorant stabilizingadditive can also optionally be a basic fuschin hydrazone, representedby the following structure: ##STR31##

The colorant solution may be stabilized with about 0.1% to 15% wt/wthydrazone, more preferably about 0.5% to 10% wt/wt hydrazone, and morepreferably about 1% to 5% wt/wt hydrazone.

In addition, another embodiment of the colorant stabilizing additive ofthis invention as described in Example 41, is a benzophenone, of thegeneral formula: ##STR32## wherein R represents any substituents whichpermit the benzophenone to function as a colorant stabilizer. Suitablesubstituents include substituents which improve the solubility of thebenzophenone in aqueous solutions and/or provide a high electron densitynext to the aromatic ring of the benzophenone. Suitable substituentsinclude, but are not limited to, hydroxyl groups, alkyl ether groups,aryl ether groups, sulfonic acid groups and sodium carboxylate groups.The colorant solution may be stabilized with about 0.01% to 15% wt/wtbenzophenone, more preferably about 0.3% to 5% wt/wt benzophenone, andmore preferably about 0.5% to 1% wt/wt benzophenone.

Although not wanting to be limited by the following, it is theorizedthat the above stabilizing compounds of the present invention, eitheradmixed with a colorant solution or on or in a substrate to which thecolorant is applied, act by quenching the excited state of a dyemolecule by efficiently returning it to a ground state. This reduces thelikelihood of an oxidative or other chemical reaction occurring whichwould render the dye chromophore colorless.

The quenching process can occur by a number of processes. One suchprocess is referred to as the heavy atom effect (internal or external)in which atoms with a high atomic number, such as iodine, xenon andlanthanides, can effect the excited electronic transitions of the dyemolecule by allowing here to fore forbidden electronic transitions tooccur and by decreasing the excited state lifetimes. This effect permitsthe rapid return of the dye to its ground state.

Another quenching process involves back electron transfer. In this case,quenching of the excited dye molecule occurs through sequential electrontransfer. The additive or quencher, and dye form an ion pair throughelectron donation within which back electron transfer leads to anoverall deactivation of the excited energy donor, i.e., the dye.

Another quenching process involves a condition in which the quencher(additive) molecule has an excited energy state lower than the exciteddye. In this case, it may be possible to transfer the excited energy tothe quencher thereby allowing the dye molecule to return to its groundstate. These mechanisms are more fully discussed in Chemistry and Light,Suppan, P., Published by The Royal Society of Chemistry, 1994, pgs 65-69which is incorporated herein by reference.

In all cases, it is optionally desirable to add a molecular includant tothe colorant solution. The molecular includant can be inorganic ororganic in nature. In certain embodiments, the chemical structure of themolecular includant is adapted to form a molecular inclusion complex.Examples of molecular includants are, by way of illustration only,clathrates or intercalates, zeolites, and cyclodextrins. Examples ofcyclodextrins include, but are not limited to, α-cyclodextrin,β-cyclodextrin, γ-cyclodextrin, δ-cyclodextrin, hydroxypropylβ-cyclodextrin, hydroxyethyl β-cyclodextrin, hydroxyethyl αcyclodextrin, carboxymethyl α cyclodextrin, carboxymethyl βcyclodextrin, carboxymethyl γ cyclodextrin, octyl succinated αcyclodextrin, octyl succinated β cyclodextrin, octyl succinated γcyclodextrin and sulfated β cyclodextrin and sulfated γ-cyclodextrin(American Maize-Products Company, Hammond, Ind.).

The term "derivatized cyclodextrin" as used herein means a cyclodextrinhaving more than two leaving groups covalently coupled to each moleculeof cyclodextrin. The term "leaving group" is used herein to mean anyleaving group capable of participating in a bimolecular nucleophilicsubstitution reaction. Examples of derivatized cyclodextrin includes,but is not limited to, hydroxypropyl β-cyclodextrin, hydroxyethylβ-cyclodextrin, hydroxyethyl α cyclodextrin, carboxymethyl αcyclodextrin, carboxymethyl β cyclodextrin, carboxymethyl γcyclodextrin, octyl succinated α cyclodextrin, octyl succinated βcyclodextrin, octyl succinated γ cyclodextrin and sulfated β andγ-cyclodextrin. A desired derivatized cyclodextrin is ethylhydroxyβ-cyclodextrin.

A desired molecular includant is γ-cyclodextrin. Another desirablemolecular includant is β-cyclodextrin. In other embodiments, themolecular includant is an ethyl hydroxy β-cyclodextrin. Although notwanting to be bound by the following theory, it is believed that themolecular includant inhibits the aggregation of the colorant molecule insolution. Other aggregation inhibitors that can be used in practicingthe present invention are starches, pectins, amyloses, clathrates andthe crown ethers. It is to be understood that the addition ofderivatized cyclodextrins to an ink formulation for the purpose ofinhibiting aggregation and/or stabilizing the dyes in the inks isconsidered one aspect of the present invention.

In some embodiments, the colorant and the colorant stabilizers areassociated with the molecular includant. The term "associated", in itsbroadest sense, means that the colorant and/or the colorant stabilizersare at least in close proximity to the molecular includant. For example,the colorant and/or the colorant stabilizers can be maintained in closeproximity to the molecular includant by hydrogen bonding, van der Waalsforces, ionic bonding, hydrogen bonding, dipole-dipole interactions orthe like.

Alternatively, either or both of the colorant and the colorantstabilizers can be covalently bonded to the molecular includant. Incertain embodiments, the colorant will be associated with the molecularincludant by means of hydrogen bonding and/or van der Waals forces orthe like, while the stabilizing molecule is covalently bonded to themolecular includant. In other embodiments, the colorant is at leastpartially included within the cavity of the molecular includant, and thecolorant stabilizer is located outside of the cavity of the molecularincludant.

As a practical matter, the colorant, the colorant stabilizer andmolecular includant are likely to be solids depending upon theconstituents used to prepare the molecules. However, any or all of suchmaterials can be a liquid. The colored composition can be a liquideither because one or more of its components is a liquid, or, when themolecular includant is organic in nature, a solvent is employed.Suitable solvents include, but are not limited to, amides, such asN,N-dimethylformamide; sulfoxides, such as dimethylsulfoxide; ketones,such as acetone, methyl ethyl ketone, and methyl butyl ketone; aliphaticand aromatic hydrocarbons, such as hexane, octane, benzene, toluene, andthe xylenes; esters, such as ethyl acetate; water; and the like. Whenthe molecular includant is a cyclodextrin, particularly suitablesolvents are the amides and sulfoxides.

In an embodiment where the composition of the present invention is asolid, the effectiveness of the above compounds on the colorant isimproved when the colorant and the selected compounds are in intimatecontact or in an association that approaches van der Waals radii. Tothis end, the thorough blending of the components, along with othercomponents which may be present, is desirable. Such blending generallyis accomplished by any of the means known to those having ordinary skillin the art. When the colored composition includes a polymer, blending isfacilitated if the colorant and the colorant stabilizer are at leastpartly soluble in softened or molten polymer. In such case, thecomposition is readily prepared in, for example, a two-roll mill.Alternatively, the composition of the present invention can be a liquidbecause one or more of its components is a liquid.

For some applications, the composition of the present inventiontypically will be utilized in particulate form. In other applications,the particles of the composition should be very small. Methods offorming such particles are well known to those having ordinary skill inthe art.

The colored composition optionally may also contain a carrier, thenature of which is well known to those having ordinary skill in the art.For many applications, the carrier will be a polymer, typically athermosetting or thermoplastic polymer, with the latter being the morecommon.

Examples of thermoplastic polymers include, but are not limited to:end-capped polyacetals, such as poly(oxymethylene) or polyformaldehyde,poly(trichloroacetaldehyde), poly(n-valeraldehyde), poly(acetaldehyde),poly(propionaldehyde), and the like; acrylic polymers, such aspolyacrylamide, poly(acrylic acid), poly(methacrylic acid), poly(ethylacrylate), poly(methyl methacrylate), and the like; fluorocarbonpolymers, such as poly(tetrafluoroethylene), perfluorinatedethylenepropylene copolymers, ethylene-tetrafluoroethylene copolymers,poly-(chlorotrifluoro-ethylene), ethylene-chlorotrifluoroethylenecopolymers, poly(vinylidene fluoride), poly(vinyl fluoride), and thelike; epoxy resins, such as the condensation products of epichlorohydrinand bisphenol A; polyamides, such as poly(6-aminocaproic acid) orpoly(ε-caprolactam), poly(hexamethylene adipamide), poly(hexamethylenesebacamide), poly(11-aminoundecanoic acid), and the like; polyaramides,such as poly(imino-1,3-phenyleneiminoisophthaloyl) or poly(m-phenyleneisophthalamide), and the like; parylenes, such as poly-p-xylylene,poly(chloro-p-xylene), and the like; polyaryl ethers, such aspoly(oxy-2,6-dimethyl-1,4-phenylene) or poly(p-phenylene oxide), and thelike; polyaryl sulfones, such aspoly(oxy-1,4-phenylenesulfonyl-1,4-phenyleneoxy-1,4-phenylene-isopropylidene-1,4-phenylene),poly(sulfonyl- 1,4-phenyleneoxy-1,4-phenylenesulfonyl-4,4-biphenylene),and the like; polycarbonates, such as poly(bisphenol A) orpoly(carbonyldioxy-1,4-phenyleneisopropylidene-1,4-phenylene), and thelike; polyesters, such as poly(ethylene terephthalate),poly(tetramethylene terephthalate), poly(cyclohexylene-1,4-dimethyleneterephthalate) orpoly(oxy-methylene-1,4-cyclohexylenemethyleneoxyterephthaloyl), and thelike; polyaryl sulfides, such as poly(p-phenylene sulfide) orpoly(thio-1,4-phenylene), and the like; polyimides, such aspoly(pyromellitimido-1,4-phenylene), and the like; polyolefins, such aspolyethylene, polypropylene, poly(1-butene), poly(2-butene),poly(l-pentene), poly(2-pentene), poly(3-methyl-1-pentene),poly(4-methyl-1-pentene), 1,2-poly-1,3-butadiene,1,4-poly-1,3-butadiene, polyisoprene, polychloroprene,polyacrylonitrile, poly(vinyl acetate), poly(vinylidene chloride),polystyrene, and the like; and copolymers of the foregoing, such asacrylonitrile-butadienestyrene (ABS) copolymers,styrene-n-butylmethacrylate copolymers, ethylene-vinyl acetatecopolymers, and the like.

Some of the more commonly used thermoplastic polymers includestyrene-n-butyl methacrylate copolymers, polystyrene, styrene-n-butylacrylate copolymers, styrene-butadiene copolymers, polycarbonates,poly(methyl methacrylate), poly(vinylidene fluoride), polyamides(nylon-12), polyethylene, polypropylene, ethylene-vinyl acetatecopolymers, and epoxy resins.

Examples of thermosetting polymers include, but are not limited to,alkyd resins, such as phthalic anhydride-glycerol resins, maleicacid-glycerol resins, adipic acid-glycerol resins, and phthalicanhydride-pentaerythritol resins; allylic resins, in which such monomersas diallyl phthalate, diallyl isophthalate diallyl maleate, and diallylchlorendate serve as nonvolatile cross-linking agents in polyestercompounds; amino resins, such as aniline-formaldehyde resins, ethyleneurea-formaldehyde resins, dicyandiamide-formaldehyde resins,melamine-formaldehyde resins, sulfonamide-formaldehyde resins, andurea-formaldehyde resins; epoxy resins, such as cross-linkedepichlorohydrin-bisphenol A resins; phenolic resins, such asphenol-formaldehyde resins, including Novolacs and resols; andthermosetting polyesters, silicones, and urethanes.

In addition to the colorant, colorant stabilizer, and optional molecularincludant, the colored composition of the present invention also cancontain additional components, depending upon the application for whichit is intended. Examples of such additional components include, but arenot limited to, charge carriers; stabilizers against thermal oxidation;viscoelastic properties modifiers; cross-linking agents; plasticizers;charge control additives such as a quaternary ammonium salt; flowcontrol additives such as hydrophobic silica, zinc stearate, calciumstearate, lithium stearate, polyvinylstearate, and polyethylene powders;fillers such as calcium carbonate, clay and talc; surfactants; chelatingagents; and TINUVIN® compounds; among other additives used by thosehaving ordinary skill in the art. Charge carriers are well known tothose having ordinary skill in the art and typically are polymer-coatedmetal particles. Desirable surfactants include , but are not limited to,C₁₂ to C₁₈ surfactants such as cetyl trimethyl ammonium chloride andcarboxymethylamylose. TINUVIN® compounds are a class of compoundsproduced by Ciba-Geigy Corporation, which includes benzophenones,benzotriazoles and hindered amines. Desirable TINUVIN® compoundsinclude, but are not limited to,2-(2'-hydroxy-3'-sec-butyl-5'-tert-butylphenyl)-benzo-triazole,poly-(N-β-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxy-piperidyl succinateand 2-(2'-hydroxy-3',5'-ditert butylphenyl)-5-chloro-benzotriazole. Theidentities and amounts of such additional components in the coloredcomposition are well known to one of ordinary skill in the art.

When the colorant stabilizers of the present invention are used tostabilize the dyes in ink jet inks, it is desirable to filter thecompositions through a small pore filter (0.45μ) such as a Millipore®filter before the ink formulation is placed in an ink jet cartridge.This will reduce or eliminate clogging of the cartridge ink nozzles dueto particulate matter.

The colorant stabilizers of the present invention enable the formationof ink sets, wherein each ink of the ink set, regardless of color,possesses similar light fastness properties as the other inks in the inkset. Such ink sets may be used to produce multi-color text and/orgraphics, which uniformly retain their color over extended periods oftime and/or upon extended exposure to light. One desirable ink setincludes cyan, magenta, yellow and black inks, wherein the magenta inkcontains colorant stabilizers in the form of a porphine and a metal,such as europium, and the yellow ink contains a colorant stabilizer inthe form of a porphine without the metal. Another desirable ink setincludes cyan, magenta, yellow and black inks, wherein the cyan inkcontains a colorant stabilizer in the form of a benzophenone, and themagenta and yellow inks contain colorant stabilizers in the form of aporphine and a metal, such as europium.

It is to be understood that in any desired ink set, a single ink may bestabilized according to the present invention or several of the inks maybe stabilized utilizing one or more of the stabilizing agents describedherein. Other ink sets are within the scope of the present invention.Included in the present invention are ink sets wherein the black coloris a pigment and the other colors in the ink set are dyes. Although inksets wherein the inks possess substantially identical light fastnessproperties are desirable, in some embodiments, it may be desirable toproduce ink sets wherein the inks within the ink set have specificallycontrolled, varying light fastness properties.

Treated Substrates.

As stated above, colorant stabilizers may be present in a colorantsolution, or present on or in a substrate to which the colorant is to beapplied. When a colorant stabilizer is present in or on a substrate, thesubstrate is referred to as a "treated substrate". In one embodiment ofthe present invention, a treated substrate contains a reducing agentthereon or therein. In another embodiment, a treated substrate containsa molecular includant thereon or therein. In yet another embodiment, atreated substrate contains a molecular includant and a reducing agentthereon or therein. The term "stabilizing agent" is used to denote thecolorant stabilizer in or on a substrate.

The substrate may be, but is not limited to, paper, wood, a wood productor composite, woven fabric, nonwoven fabric, textile, plastic, glass, orany other substrate that would benefit from having a stabilized colorantthereon. A plastic substrate includes, but is not limited to, a plasticfilm, a plastic nonwoven web, or a plastic woven web. A preferredsubstrate is paper. Any existing or future type of paper or paperproducts may be used in the present invention.

Examples of paper or paper products include, but not limited to,printing and writing papers, packaging and industrial papers,paperboard, and tissue papers. Examples of printing and writing papersinclude, but are not limited to the following: wood-free coated papers;wood-containing coated papers; wood-free uncoated papers such as bondand writing paper, envelopes, offset and opaque circular, carbonless,tablet, forms bond, ledger, mimeograph, and manifold, duplication, faxbase, thermal base, technical papers, supercalandered, and specialtypapers; uncoated wood-containing papers such as supercalandered,directory, specialty converting and publishing; bristols such as coatedbristols, uncoated bleached bristols, tag, coated tag papers, filefolders, and tabulating; and thin papers such as cigarette paper, biblepaper, lightweight paper, lightweight specialty, manifold, cotton fiberpapers, and specialty thin papers.

Examples of Packaging and industrial papers include, but are not limitedto the following: breached Kraft paper such as grocers bags, shippingsacks, wrapping paper, and converting paper; unbleached Kraft paper suchas grocers bags, shipping sacks converting paper, wrapping paper, andenvelopes. Examples of paperboard include, but are not limited to thefollowing: containerboard such as unbleached linerboard, bleachedlinerboard, corrugated medium, and chip and filler board; foldingboxboard/folding cartonboard such as solid bleached sulfite, bleachedand unbleached bristols, coated recycled board, coated unbleached Kraft,milk, cup, plate and foodservice stock (coated or uncoated), and foldingboard; gypsum wallboard; and tube/can and drum paperboard. Examples oftissue papers include, but are not limited to, sanitary tissues such asbathroom tissue, facial tissue, napkins, toweling, wiper stock, andother sanitary tissue papers.

Molecular Includant

pAs stated above, a molecular includant is defined as any substancehaving a chemical structure which defines at least one cavity, wherein acavity includes any opening or space of a size sufficient to accept atleast a portion of a compound, such as, but not limited to, a colorant.The molecular includant can be inorganic or organic in nature. Incertain embodiments, the chemical structure of the molecular includantis adapted to form a molecular inclusion complex. Molecular includantsinclude, but are not limited to, clathrates or intercalates, zeolites,crown ethers, calixarenes, valinomycin type natural antibiotics, variouspolyether compounds, nigericin type natural antibiotics, or cycliccompounds containing a plurality of pyranose rings, for example, thosehaving formed cyclic compounds through 1,4 and 1,6 bonding ofmonosaccharides such as glucose, fructose, galactose, and the like, anddisaccharides such as saccharose, maltose, lactose, and the like.

The cyclic compounds also include cyclodextrins such asalpha-cyclodextrin (or α-cyclodextrin), beta-cyclodextrin (orβ-cyclodextrin), gamma-cyclodextrin (or γ-cyclodextrin),delta-cyclodextrin (or δ-cyclodextrin), and derivatives thereof such ashydroxypropyl β-cyclodextrin, hydroxyethyl β-cyclodextrin, hydroxyethylα-cyclodextrin, carboxymethyl α-cyclodextrin, carboxymethylβ-cyclodextrin, carboxymethyl γ-cyclodextrin, octyl succinated αcyclodextrin, octyl succinated β-cyclodextrin, octyl succinatedγ-cyclodextrin, sulfated β-cyclodextrin and sulfated γ-cyclodextrin,hydroxyethyl γ-cyclodextrin, hydroxyisopropyl γ-cyclodextrin,hydroxypropyl γ-cyclodextrin, octyl succinate γ-cyclodextrin, andcarboxymethyl γ-cyclodextrin.

The α-cyclodextrins contain 6 glucopyranose rings, the β-cyclodextrinscontain 7 glucopyranose rings, the γ-cyclodextrins contain 8glucopyranose rings, and the δ-cyclodextrins contain 9 glucopyranoserings. Cyclodextrins with 10, 11, or 12 glucopyranose rings may also beused in the present invention. A desirable cyclodextrin is anyγ-cyclodextrin that is water soluble. In particular, hydroxyethylγ-cyclodextrin, hydroxyisopropyl γ-cyclodextrin, and hydroxypropylγ-cyclodextrin are desirable molecular includants for the presentinvention. Another desirable cyclodextrin is any β-cyclodextrin that iswater soluble. In particular, hydroxyethyl β-cyclodextrin is a preferredcyclodextrin.

The cyclodextrins suitable for the inks of the present invention canalso, if desired, be modified by the addition of substituents.Substituents generally replace either the entire hydroxyl group or thehydrogen atom on one or more of the hydroxyl groups of the cyclodextrinring. Examples of substituents include acyl groups, wherein one or moreof the hydroxyl groups is replaced with groups such as --OAc, --OC(O)CH₂CH₃, --OC(O)(CH₂)₂ CH₃, --OC(O)(CH₂)₃ CH₃, --OC(O)CF₃, --OC(O)Ph, or thelike; alkyl and aryl groups, wherein one or more of the hydroxyl groupsis replaced with groups such as --OCH₃, --OCH₂ CH₃, --O(CH₂)₂ CH₃,--OC(CH₃)₃, --OPh, or the like; tosyl (4-methylbenzenesulfonyl), or Tsor related groups, wherein one or more of the hydroxyl groups isreplaced with --OTs or the like; mesyl (methanesulfonyl, or Ms) orrelated groups, wherein one or more of the hydroxyl groups is replacedwith --OMs or the like; amino groups, wherein one or more of thehydroxyl groups is replaced with groups such as a primary, secondary, ortertiary amine group, including cyclic amines and aromatic amines or thelike; azido groups, wherein one or more of the hydroxyl groups isreplaced with --N₃ or the like; halo substituents, wherein one or moreof the hydroxyl groups is replaced with a halogen atom, such as --F,--Cl, --Br, or --I; nitro groups, wherein one or more of the hydroxylgroups is replaced with --ONO₂ ; phosphorus-containing groups, whereinone or more of the hydroxyl groups is replaced with groups such as--OPO₃ H₂, --OPO₃ R₂ (wherein R is alkyl or aryl), --OPO₃ HR, or whereintwo adjacent hydroxyl groups are replaced with groups such as--OP(O)(CH₃)O--, or the like; imidazole groups and their derivatives;pyridine groups and their derivatives; sulfur-containing functionalgroups, wherein one or more of the hydroxyl groups is replaced withgroups such as --SCH₃, --SCH₂ CH₃, --S(CH₂)₂ CH₃, --SC(CH₃)₃, --OSO₃ ⁻Na⁺, --OCH₂ SO₃ ⁻ Na⁺, --OCH₂ CH₂ SO₃ ⁻ Na⁺, --O(CH₂)₃ SO₃ ⁻ Na⁺, or thelike; alcohol, aldehyde, ketone, or oxime groups; carboxylic acid groupsand their derivatives; carbonate and carbamate groups; silicon, boron,or tin containing groups, wherein one or more of the hydroxyl groups isreplaced with groups such as --OSi(CH₃)₃, --OSi(CH₃)₂ H, --CH₂OSi(CH₃)₃, --CH₂ OSi(CH₃)₂ H, --OB (CH₂ CH₂)₂, --CH₂ OB(CH₂ CH₂)₂, --CH₂OSn((CH₂)₃ CH₃)₃, or the like; hydroxyalkyl groups, such as hydroxyethyl groups, hydroxypropyl groups, or the like; or any other suitablesubstituent.

In another embodiment, substituent or substituents in the cyclodextrinmolecules are bonded to an oxygen atom in a ring glucose unit. Forexample, the substituent can be an alkyl radical, desirably having up toabout six carbon atoms. Another example of such a substituent has theformula --(CH--CHR¹ --O--)n--H wherein R¹ is selected from the classconsisting of hydrogen and alkyl groups having up to about six carbonatoms. In the above formula, n is a small whole number having a value upto about six; desirably, n is equal to 1. Preferred substituents of thistype are hydroxyethyl and hydroxypropyl.

Yet another type of substituent on the cyclodextrin is a bridging groupthat links two cyclodextrin moieties. The bridging groups have theformula --CHR¹ --CHOH--CHR¹ -- wherein R¹ has the same significance asabove. In these polymeric cyclodextrins, the number of cyclodextrinrings so bridged is from two to about six. In other words, there can betwo cyclodextrin rings linked by the bridging group, or there can bethree of the rings linked by two bridging groups, and so on, such thatthere can be six rings linked by five bridging groups. It is to beunderstood that higher polymers can be used in the invention if theyhave properties analogous to the polymers within the range given above,and the increased size or molecular weight does not confer anundesirable property to the extent that it makes the material unsuitablefor use in the invention. The polymeric cyclodextrins may havesubstituents in addition to the group that links or bridges twocyclodextrin moieties. For example, the cyclodextrin moieties may haveone or more carboxyalkyl (--R--COOH) substituents, wherein R is a loweralkylene radical having up to about 4 carbon atoms.

Cyclodextrin rings can also be bound together to form polymers byprocesses such as linking the cyclodextrin rings together with suitablemultifunctional agents. For example, a poly-β-cyclodextrin can be formedthat is crosslinked with epichlorohydrin; this material is commerciallyavailable from American Tokyo Kasei, Inc., 9211 N. Harborgate St.,Portland, Oreg. 97203. It is to be understood that any method known toone of ordinary skill in the art may be used to covalently bind two ormore molecular includants together. A desired embodiment is to havecrosslinked γ-cyclodextrins in or on a substrate.

Cyclodextrins are commercially available from, for example, AmericanMaize-Products Company, of Hammond, Indiana. Additional informationregarding cyclodextrins and modified cyclodextrins is widely availablein the chemical literature, and is summarized in, for example,"Synthesis of Chemically Modified Cyclodextrins," A. P. Croft and R. A.Bartsch, Tetrahedron, Vol. 39, No. 9, pages 1417 to 1474 (1983), thedisclosure of which is totally incorporated herein by reference.Substituted cyclodextrins are also shown in the publication "Molecusol™:Your Research Solution," Pharmetec, Inc. (1988), the disclosure of whichis totally incorporated herein by reference. The hydroxypropylsubstituted cyclodextrin is also suitable for the prevent invention.

Additionally, it is to be understood that the molecular includants ofthe present invention may have one or more of the stabilizer moleculesdiscussed above, which may be admixed into a colorant solution,associated therewith. The term "associated", in its broadest sense,means that the stabilizer molecule is at least in close proximity to themolecular includant. For example, the stabilizer molecule can bemaintained in close proximity to the molecular includant by hydrogenbonding, van der Waals forces, ionic bonding, hydrogen bonding,dipole-dipole interactions or the like.

The molecular includant in association with a colorant stabilizes thecolorant. More particularly, the molecular includant stabilizes acolorant when it is present on or in the substrate upon which thecolorant is applied.

In the embodiment where the molecular includant is present on or in thesubstrate, the molecular includant may be introduced onto or into thesubstrate by any method known to one of ordinary skill in the art,wherein the method does not destroy the molecular includant's ability tostabilize a colorant. In one embodiment, a treated substrate is onewherein the molecular includant is applied to the substrate in solutionform and the substrate is subsequently dried to produce the substrate inthe form it is to be utilized. Any substrate may be used, wherein thesubstrate does not destroy the molecular includant's ability tostabilize a colorant. A preferred substrate is paper. Any existing orfuture type of paper or paper products may be used in the presentinvention.

The molecular includant may be applied while the substrate is beingmanufactured, or it may be applied after the substrate has beenmanufactured. Where the substrate is paper, the molecular includant maybe admixed into the pulp during the process of manufacturing the paper.An amount of molecular includant is admixed with the pulp so that thepaper produced contains an amount of molecular includant effective tostabilize a colorant thereon. Desirably, between approximately 30 to 80%molecular includant by weight is admixed with the pulp. More desirably,between 50 to 65% molecular includant by weight is admixed with thepulp. A desirable amount of molecular includant in the final paperproduct is between 3% and 50% wt/wt. A more desired amount of molecularincludant in the paper product is between 5 and 20%. Even more desiredis between 7 and 10% of molecular includant in the paper product. Anymethod known in the art may be used to admix the molecular includantwith the pulp, and produce the final paper product, wherein themolecular includant maintains its ability to stabilize a colorant. Theabove also applies to the manufacturing of wood pulp or compositesubstrates.

Alternatively, the molecular includant may be applied to a substrateafter it has been manufactured, by dipping the substrate in a solutionof the molecular includant, spraying the substrate, coating thesubstrate, or soaking the substrate with a solution of the molecularincludant. Any method known in the art to apply a solution to asubstrate and to dry the substrate may be used in the present inventionso long as the molecular includant maintains its ability to stabilize acolorant. An amount of molecular includant solution is applied to thesubstrate so that after drying, the substrate contains an amount ofmolecular includant effective to stabilize a colorant thereon ortherein.

Desirably, the concentration of the molecular includant solution isbetween 3% and 80% wt/wt. A more desired concentration is between 5 and65%. An even more desired concentration is between 10 and 50%. Adesirable amount of molecular includant in or on the treated substrateis between 1% and 50% wt/wt. A more desired amount of molecularincludant in or on the treated substrate is between 3 and 25%. Even moredesired is between 5 and 20% of molecular includant in or on the treatedsubstrate. One embodiment of coating a molecular includant onto paper isfully described in Example 34.

In another embodiment, both the molecular includant and the colorant maybe present within the substrate. The molecular includant and thecolorant may be admixed with paper pulp, wood pulp, or monomers oroligomers, during the process of manufacturing paper, wood products, orplastics respectively. Alternatively, one of the above components can beintroduced during the manufacturing process and the second component canbe applied after the manufacturing process.

Examples 35 and 36 report the fade testing results of various magentainks on treated and untreated paper. The magenta inks were studied asthey tend to be the least stable of the widely used inks. Moreparticularly, Hewlett-Packard (HP), American Ink Jet (AIJ), and Canonmagenta ink jet inks, either with or without the stabilizing additivesof the present invention, were printed on treated and untreatedHewlett-Packard premium paper and then exposed to an Atlas Weatherometerfor a total of 77 hours. The inks containing the additives of thepresent invention contained 5% wt/wt of the basic fuschin imine adductprepared in Example 7, 0.25 eq of tetramethylammonium iodide, and 2%wt/wt of hydroxyethyl β-cyclodextrin. It is to be understood that themolar equivalents of the various stabilizing compounds can be varied.

In Example 35, the treated paper was coated with γ-cyclodextrin asdescribed in Example 34, such that the treated paper contained 7% wt/wtof the γ-cyclodextrin. After 77 total hours of exposure the change ofcolor is measured and the ΔE* values compared. The ΔE* values reportedin Example 35 for the HP and AIJ inks show that the molecular includantis an effective colorant stabilizer without the presence of additionalstabilizing additives. More particularly, the ΔE* value for HP ink withno additives on untreated paper is 64, whereas the value for HP ink withno additives on cyclodextrin coated paper is 31.5. The ΔE* value for AIJink with no additives on untreated paper is 37, whereas the value forAIJ ink with no additives on cyclodextrin treated paper is 13.7.

Additionally, the ΔE* values reported in Example 35 for the HP inksshows that the additives are an effective colorant stabilizer withoutthe presence of the molecular includant in the paper. More particularly,the ΔE* value for HP ink with additives on untreated paper is 25.0,whereas the ΔE* value for HP ink with no additives on untreated paper is64.0.

The ΔE* values reported in Example 35 also show that the molecularincludant treated paper with the additive-containing ink yieldsunexpectedly superior colorant stabilization results. More particularly,the ΔE* value for HP ink with no additives on untreated paper is 64,with no additives on treated paper is 31.5, with additives on untreatedpaper is 25.0, and with additives on treated paper is 14.7. Accordingly,the ΔE* values show that although the additives alone stabilize the HPand AIJ inks, and treated paper alone stabilizes the HP and AIJ inks,the most lightfast colorant is stabilized by being associated with theadditives in the solution and being printed on the treated paper.

In Example 36, three types of treated paper were studied along side ofan uncoated paper. More particularly, HP Premium Ink Jet paper wastreated with a 50% γ-cyclodextrin solution, a 20% sodium thiosulfatesolution, or a 20% γ-cyclodextrin/10% sodium thiosulfate solution. Theuncoated paper that was also studied is Kimberly-Clark Bright Whitepaper. After printing, and exposure in the Atlas Weatherometer for 77hours, the ΔE* values were measured.

The ΔE* values reported in Example 36 also show that although theadditives alone stabilize the HP and AIJ inks, and treated paper alonestabilizes the HP and AIJ inks, the most lightfast colorant isstabilized by being associated with the additives in the solution andbeing printed on the treated paper.

With respect to the Bright White paper stabilization results reported inExample 36, these results are not readily comparable to thestabilization results obtained regarding the HP Premium paper. Moreparticularly, most ink jet papers are coated so that the ink is notabsorbed into the fibers of the paper and instead remains on the surfaceof the paper. The coated paper thereby produces a superior ink jetprinting quality. The HP Premium paper is an example of such a coatedpaper.

In contrast, the Kimberly-Clark Bright White paper is not a coatedpaper. Accordingly, when an ink is printed thereon, the ink is wicked orabsorbed into the bulk of the fibers of the paper, and does not remainon the surface of the paper, thereby yielding a different quality ofprinting. Although not wanting to be bound by the following, it istheorized that the ink that is absorbed into the uncoated paper isprotected from degradation from light by the fibers of the paper. Incontrast, inks that are printed on coated paper remain on the surface ofthe paper and receive no protection from the fibers of the paper.Accordingly, the stability and quality of printing of inks that areprinted on an uncoated paper cannot be compared directly to inks thatare printed on coated paper.

Reducing Agent

In the embodiment where the treated substrate contains a reducing agent,the reducing agent may be, but is not limited to, sodium thiosulfate(Na₂ S₂ O₃), sodium sulfite (Na₂ SO₃), cysteine, sodium nitrite, sodiumphosphite, sodium citrate, citric acid, ascorbic acid, boron hydride,dithionite, hydrazine, thiourea-dioxide, hydrogen sulphite, potassiumsulfite, ammonium sulfite, sodium hydrogen sulfite, potassium hydrogensulfite, ammonium hydrogen sulfite, sodium trithionite, and polyhydricphenols. A desired reducing agent is sodium thiosulfate.

The reducing agent in association with a colorant stabilizes thecolorant. The reducing agent stabilizes a colorant when it is present onor in the substrate upon which the colorant is applied, or when it isadmixed with the colorant prior to its application to the substrate.Also, the reducing agent may be present both on or in the substrate uponwhich the colorant is applied and admixed with the colorant prior to itsapplication. Additionally, the reducing agent may be applied to thecolorant after the colorant has been applied to a substrate.

In the embodiment where the reducing agent is present on or in thesubstrate, the reducing agent may be introduced onto or into thesubstrate by any method known to one of ordinary skill in the art,wherein the method does not destroy the reducing agent's ability tostabilize a colorant. The reducing agent may be applied while thesubstrate is being manufactured, or it may be applied after thesubstrate has been manufactured. It is to be understood that when areducing agent is present on or in a substrate in the form it is to beutilized, the substrate is referred to as a "treated substrate". In oneembodiment, a treated substrate is one wherein the reducing agent wasapplied to the substrate in solution form and the substrate has beensubsequently dried to produce the substrate in the form it is to beutilized.

Any substrate may be used, wherein the substrate does not destroy thereducing agent's ability to stabilize a colorant. As stated above, thesubstrate may be, but is not limited to, paper, wood, a wood product orcomposite, woven fabric, nonwoven fabric, textile, plastic, glass, orany other substrate that would benefit from having a stabilized colorantthereon. A preferred substrate is paper. Any existing or future type ofpaper may be used in the present invention, including, but not limitedto, newsprint, coated wood containing paper, super calendared paper,fine paper, paperboard, and ink jet paper.

Where the substrate is paper, the reducing agent may be admixed into thepulp during the process of manufacturing the paper. An amount ofreducing agent is admixed with the pulp so that the paper producedcontains an amount of reducing agent effective to stabilize a colorantthereon. Desirably, between approximately 2 to 50% reducing agent byweight is admixed with the pulp. More desirably, between 3 to 30%reducing agent by weight is admixed with the pulp. A desirable amount ofreducing agent in the final paper product is between 1% and 50% wt/wt. Amore desired amount of reducing agent in the paper product is between 2and 20%. Even more desired is between 3 and 10% of reducing agent in thepaper product. Any method known in the art may be used to admix thereducing agent with the pulp, and produce the final paper product,wherein the reducing agent maintains its ability to stabilize acolorant. The above also applies to the manufacturing of wood pulp orcomposite substrates.

Alternatively, the reducing agent may be applied to a substrate after ithas been manufactured, or in its final form, by dipping the substrate ina solution of the reducing agent, spraying the substrate, coating thesubstrate, or soaking the substrate with a solution of the reducingagent. Any method known in the art to apply a solution to a substrateand to dry the substrate may be used in the present invention so long asthe reducing agent maintains its ability to stabilize a colorant. Anamount of reducing agent solution is applied to the substrate so thatafter drying, the substrate contains an amount of reducing agenteffective to stabilize a colorant thereon or therein.

Desirably, the concentration of the reducing agent solution is between1% and 50% wt/wt. A more desired concentration is between 3 and 40%. Aneven more desired concentration is between 5 and 20%. A desirable amountof reducing agent in or on the treated substrate is between 1% and 50%wt/wt. A more desired amount of reducing agent in or on the treatedsubstrate is between 2 and 20%. Even more desired is between 3 and 10%of reducing agent in or on the treated substrate. One method of coatinga substrate with a reducing agent is fully described in Example 34.

In another embodiment, both the reducing agent and the colorant may bepresent within the substrate. The reducing agent and the colorant may beadmixed with paper pulp, wood pulp, or monomers or oligomers, during theprocess of manufacturing paper, wood products, or plastics respectively.Alternatively, one of the above components can be introduced during themanufacturing process and the second component can be applied after themanufacturing process.

In yet another embodiment, the colorant and reducing agent are admixedin one solution and applied to a substrate simultaneously. For example,a colorant and an amount of reducing agent effective to stabilize thecolorant can be in an ink jet ink cartridge in an ink jet printer. It isto be understood that any commercially available ink can be admixed witha reducing agent to stabilize the colorant therein. Desirably, theconcentration of the reducing agent in ink is between 1 and 50% byweight. A more desired concentration is between 3 and 40%. An even moredesired concentration is between 5 and 20%.

Examples 30 and 31 report the fade testing results of Hewlett Packardyellow ink printed on sodium thiosulfate treated paper and untreatedpaper. More particularly, yellow Hewlett Packard ink was printed onuntreated paper and paper that had been dipped in a 10% wt/wt aqueoussodium thiosulfate solution and then dried. The papers were then exposedto an Atlas Weatherometer for a total of 51 hours. Visual and colormeasurements (ΔE*) show that the treated paper reduces the fade of theyellow ink. In particular, the ΔE* values after 24 hours were 28.33 forthe untreated paper, and 2.29 for the treated paper. The ΔE* valuesafter 51 hours were 54.96 for the untreated paper, and 12.08 for thetreated paper. Accordingly, the ΔE* values indicate little or no colorchange of the yellow ink on the treated paper over 51 the hours ofexposure. These ΔE* values therefore show that the reducing agent is aneffective colorant stabilizer.

Although the reducing agent alone stabilizes a colorant, it is alsodesirable that the reducing agent be utilized with one or more of theabove stabilizers. Example 29 reports the fade testing results ofHewlett Packard magenta ink admixed with various combinations ofstabilizing compounds of the present invention printed on treated anduntreated paper. More particularly, three molar equivalents of thetriiodophenol sugar produced in Example 25, four molar equivalents ofthe trimethylphenol sugar produced in Example 23, and two molarequivalents of sodium iodide were admixed with HP magenta ink havingalready admixed therein 5% by weight β-hydroxyethyl cyclodextrin. Thisadmixture is the additive-containing ink. It is to be understood thatthe molar equivalents of the various stabilizing compounds can bevaried.

The magenta additive-containing ink or the commercially availablemagenta Hewlett Packard ink (control) was printed on untreated paper andpaper that had been dipped in a 10% wt/wt aqueous sodium thiosulfatesolution and then dried (the treated paper). The papers were thenexposed to an Atlas Weatherometer for a total of 15 hours. Visual andcolor measurements (ΔE*) show that the control ink on untreated paperfaded the most, the additive-containing ink on untreated paper fadedless, and the additive-containing ink on treated paper barely faded atall, and faded the least. In particular, the ΔE* values are as follows:34.24 for control ink on untreated paper; 20.53 for additive-containingink on untreated paper; and 11.09 for additive-containing ink on treatedpaper. Accordingly, the ΔE* values show that although the additivesalone stabilize the magenta colorant, the reducing agent in the paperfurther stabilizes the colorant in the presence of these additives.

Additionally, the substrate itself may be treated with one or more ofthe above reducing agents, one or more of the above molecularincludants, or combinations thereof. In one embodiment, the substrate istreated with both a reducing agent and a molecular includant. Desirably,the reducing agent is sodium thiosulfate and the molecular includant isγ-cyclodextrin.

It is most desirable to treat a substrate with a reducing agent when theink to be printed thereon is relatively pure. Although not wanting to belimited by the following, it is theorized that if ink containing arelatively substantial amount of impurities is printed on reducingagent-treated paper, the reducing agent will react with the impuritiesthereby decreasing its color stabilizing properties.

It has been unexpectedly discovered that the presence of a reducingagent in paper decreases the amount of yellowing that occurs on thepaper upon exposure to the radiation. Example 28 reports the testing oftreated and untreated paper for reduction of yellowing. Moreparticularly, sheets of paper were dipped in the following: (1) a sodiumiodide and sodium thiosulfate solution; (2) a sodium iodide solution; or(3) a sodium thiosulfate solution, and then dried. The above sheets andcontrol sheets (which untreated) were placed into an Atlas Weatherometerovernight. The results are as follows: the sheets treated with solution(1) turned yellow; the sheets treated with solution (2) turned darkyellow; the sheets treated with solution (3) did not change, andremained white; and the control sheets turned a very pale yellow.

Example 28 illustrates that one of the colorant stabilizers of thepresent invention, namely, sodium iodide, increases the yellowing ofpaper. In contrast, the presence of the reducing agent, sodiumthiosulfate, inhibits the yellowing of paper. Further, the presence ofthe reducing agent decreases the amount of yellowing resulting from thesodium iodide.

The present invention is further described by the examples which follow.Such examples, however, are not to be construed as limiting in any wayeither the spirit or scope of the present invention. In the examples,all parts are parts by weight unless stated otherwise.

EXAMPLE 1

Preparation of the imine adduct.

To a 500 ml round bottomed flask is added 10.0 g chalcone (Aldrich), 8.3g 2-amino benzene sulfonic acid (Aldrich), 200 ml of absolute ethanol,and 3 drops of dimethylamino ethanol (Aldrich). The reaction mixture isrefluxed for one hour after which the solvent is removed to yield a paleyellow crystalline solid. The yield is 16.5 grams (95%). The reaction isrepresented as follows: ##STR33##

EXAMPLE 2

Preparation of triiodophenolate sodium salt

To 25 g of triiodophenol (Aldrich) in a 250 ml round bottomed flask isadded 100 ml diethyl ether. 52.5 ml of 1M sodium hydroxide (Fisher) isthen added and the solution is stirred for 1 hour. The mixture is thenrotoevaporated under reduced pressure to yield an off-brown solid whichis used without further purification.

EXAMPLE 3

Effect of triiodophenolate sodium salt and triiodophenol on degradationof magenta dye.

1.5 equivalents to dye of triiodophenolate sodium salt from Example 2 or1.5 equivalents of triiodophenol is added to 5 g of standard HewlettPackard magenta ink jet ink formulation (Hewlett Packard, Palo Alto,Calif., Part No. HP 51640 M). 2% (wt/wt) of ethyl hydroxy β-cyclodextrinis added to the ink samples. The sample is drawn down on a transparency(Hewlett-Packard, Palo Alto, Calif., Cat. No. HPC 3834A). The sample isthen exposed for 10 minutes to a fusion lamp (Fusion UV Curing SystemsCorp., Rockville, Md., Model F300+D-bulb) having a water cooled Pyrexfilter. All absorbency measurements in these Examples were made on aPerkin-Elmer UV/VIS spectrophotometer (Perkin-Elmer Corporation,Norwalk, Conn., Model LAMBDA-14P). The results are shown in thefollowing table.

    ______________________________________    Time (min)              Control   Triiodophenolate                                    Triiodophenol    ______________________________________     0        0.8       0.87        0.74    10        0.27      0.77        0.70    ______________________________________

EXAMPLE 4

Effect of sodium iodide on degradation of magenta dye.

10 and 2 equivalents of sodium iodide are added respectively to twoaliquots of 5 g of standard Hewlett Packard magenta ink jet inkformulation (Hewlett Packard, Palo Alto, Calif., Part No. HP 51640 M).2% (wt/wt) of ethyl hydroxy β-cyclodextrin is added to the ink samples.The sample is drawn down on a transparency (Hewlett-Packard, Palo Alto,Calif., Cat. No. HPC 3834A). The sample is then exposed for 10 minutesto a fusion lamp having a water cooled Pyrex filter. The results areshown in the following table.

    ______________________________________    Time (min)              Control    NaI (10 eq.)                                   NaI (2 eq.)    ______________________________________    0         0.8        0.88      0.91    2         0.55       0.88      0.9    4         0.45       0.88      0.85    6         0.37       0.84      0.79    8         0.34       0.81      0.73    10        0.27       0.77      0.7    ______________________________________

EXAMPLE 5

Effect of imine adduct on degradation of magenta dye.

1.5 equivalents of the imine adduct from Example 1 is added to 5 g ofstandard Hewlett Packard magenta ink jet ink formulation (HewlettPackard, Palo Alto, Calif., Part No. HP 51640 M). 2% (wt/wt) of ethylhydroxy β-cyclodextrin is added to the ink samples. The sample is drawndown on a transparency (Hewlett-Packard, Palo Alto, Calif., Cat. No. HPC3834A). The sample is then exposed for 10 minutes to a fusion lamphaving a water cooled Pyrex filter. The results are shown in thefollowing table.

    ______________________________________    Time (min)    Absorbency    ______________________________________     0            0.92    10            0.84    ______________________________________

EXAMPLE 6

Effect of imine adduct on degradation of cyan dye.

4 equivalents or 1.5 equivalents to dye of the imine adduct from Example1 is added to 5 g of standard Hewlett Packard cyan ink jet inkformulation (Hewlett Packard, Palo Alto, Calif., Part No. HP 51640 C).2% (wt/wt) of ethyl hydroxy β-cyclodextrin is added to the ink samples.The sample is drawn down on a transparency (Hewlett-Packard, Palo Alto,Calif., Cat. No. HPC 3834A). The samples are then exposed for 10 minutesto a fusion lamp having a water cooled Pyrex filter. The results areshown in the following table.

    ______________________________________                        Imine Adduct                                   Imine Adduct    Time (min)              Control   (4 eq.)    (1.5 eq.)    ______________________________________     0        0.83      0.92       0.83    10        0.06      0.86       0.52    ______________________________________

EXAMPLE 7

Preparation of the imine adduct of basic fuschin

A solution of 5.0 g basic fuschin (Aldrich) and 3.2 g chalcone (Aldrich)in 300 ml of absolute ethanol with 3 drops of dimethylamino ethanol isrefluxed for 1 hour after which the solvent is removed to yield a greencrystalline powder. The powder is placed under reduced pressure for 1hour. The reaction is summarized as follows, wherein the product isreferred to as "chalcone fuschin imine": ##STR34##

EXAMPLE 8

Effect of basic fuschin imine adduct on degradation of cyan ink.

As a control, basic fuschin dye (Aldrich) is dissolved in water (10%wt/wt) and applied to an HP transparency. The imine adduct from Example7 is dissolved in water (10% wt/wt). 2% (wt/wt) to dye of the imineadduct from Example 7 is added to 5 g of standard Hewlett Packard cyanink jet ink formulation (Hewlett Packard, Palo Alto, Calif., Part No. HP51640 C). 2% (wt/wt) of ethyl hydroxy P-cyclodextrin is added to the inksamples. The sample is drawn down on a transparency (Hewlett-Packard,Palo Alto, Calif., Cat. No. HPC 3834A). The sample is then exposed for10 minutes to a fusion lamp having a water cooled Pyrex filter. Theresults are shown in the following table.

    ______________________________________                           Basic Fuschin    Time (min)     Control Adduct    ______________________________________     0             0.99    0.80    10             0.38    0.78    ______________________________________

EXAMPLE 9

Effect of iodide salts on degradation of magenta dye.

10 molar equivalents of sodium iodide, potassium iodide ortetramethylammonium iodide ((CH₃)₄ NI) to dye are added to 5 g ofstandard Hewlett Packard magenta ink jet ink formulation (HewlettPackard, Palo Alto, Calif., Part No. HP 51640 M). 2% (wt/wt) of ethylhydroxy β-cyclodextrin is added to the ink samples. The sample is drawndown on a transparency (Hewlett-Packard, Palo Alto, Calif., Cat. No. HPC3834A). The samples is exposed for 10 minutes to a fusion lamp having awater cooled Pyrex filter. The results are shown in the following table.

    ______________________________________    Time             NaI        KI    (CH.sub.3).sub.4 NI    (min)    Control (10 eq.)   (10 eq.)                                      (10 eq.)    ______________________________________     0       0.80    0.96       0.73  0.80    10       0.27    0.79       0.47  0.68    ______________________________________

EXAMPLE 10

Effect of imine adduct on degradation of magenta dye under a xenon lamp.

2 molar equivalents of t he imine from Example 1 to dye is added to 5 gof standard Hewlett Packard magenta ink jet ink formulation (HewlettPackard, Palo Alto, Calif., Part No. HP 51640 M). 2% (wt/wt) of ethylhydroxy β-cyclodextrin is added to the ink samples. The sample is drawndown on a transparency (Hewlett-Packard, Palo Alto, Calif., Cat. No. HPC3834A). The sample is then exposed for 4.5 hours to a xenon lamp(Universal Systems, Inc., Azuza, Calif., 1000 Watt Short-Arc Lamp, ModelLPS-255HR,). The results are shown in the following table.

    ______________________________________    Time (hrs)     Control Imine Adduct    ______________________________________    0              0.81    0.91    4.5            0.33    0.83    ______________________________________

EXAMPLE 11

Effect of the combination of triiodophenol and tetramethylammoniumiodide on degradation of magenta dye under a fusion lamp.

2 molar equivalents of triiodophenol (Aldrich) to dye and 0.5equivalents of (CH₃)₄ NI are added to 5 g of standard Hewlett Packardmagenta ink jet ink formulation (Hewlett Packard, Palo Alto, Calif.,Part No. HP 51640 M). 2% (wt/wt) of ethyl hydroxy β-cyclodextrin isadded to the ink samples. The sample is drawn down on a transparency(Hewlett-Packard, Palo Alto, Calif., Cat. No. HPC 3834A). The samplesare exposed for 10 minutes to a fusion lamp having a water cooled Pyrexfilter. The absorbency of the transparency at zero time is 0.95 andafter 10 minutes of exposure to the fusion lamp, the absorbency is 0.86showing good stabilizing activity.

EXAMPLE 12

Effect of triiodophenol on degradation of magenta dye under a fusionlamp.

2 molar equivalents of triiodophenol (Aldrich) to dye is admixed with 5g of standard Hewlett Packard magenta ink jet ink formulation (HewlettPackard, Palo Alto, Calif., Part No. HP 51640 M). 2% (wt/wt) of ethylhydroxy β-cyclodextrin is added to the ink samples. The sample is drawndown on a transparency (Hewlett-Packard, Palo Alto, Calif., Cat. No. HPC3834A). The samples are exposed for 10, 20 and 30 minutes to a fusionlamp having a water cooled Pyrex filter. The results of the test areshown in the following table:

    ______________________________________    Time (min)    Absorbency    ______________________________________     0            0.97    10            0.97    20            0.96    30            0.83    ______________________________________

EXAMPLE 13

Effect of the combination of the imine adduct of basic fuschin andsodium iodide on degradation of magenta dye under a fusion lamp.

5% wt/wt of the imine adduct of basic fuschin from Example 7 and 1.5equivalents of sodium iodide are admixed with 5 g of standard HewlettPackard magenta ink jet ink formulation (Hewlett Packard, Palo Alto,Calif., Part No. HP 51640 M). 2% (wt/wt) of ethyl hydroxy β-cyclodextrinis added to the ink samples. The sample is drawn down on a transparency(Hewlett-Packard, Palo Alto, Calif., Cat. No. HPC 3834A). The sample isexposed for zero and 10 minutes to a fusion lamp having a water cooledPyrex filter. The results of the test are shown in the following table:

    ______________________________________    Time (min)    Absorbency    ______________________________________     0            0.83    30            0.83    ______________________________________

EXAMPLE 14

Effect of the combination of the triiodophenol and tetramethylammoniumiodide on degradation of cyan dye under a fusion lamp.

2 equivalents of triiodophenol (Aldrich) and 0.75 equivalents of (CH₃)₄NI are added to 5 g of standard Hewlett Packard cyan ink jet inkformulation (Hewlett Packard, Palo Alto, Calif., Part No. HP 51640 C).2% (wt/wt) of ethyl hydroxy β-cyclodextrin is added to the ink samples.The sample is drawn down on a transparency (Hewlett-Packard, Palo Alto,Calif., Cat. No. HPC 3834A). The samples is exposed for 10 minutes to afusion lamp having a water cooled Pyrex filter. The results of the testare shown in the following table:

    ______________________________________    Time (min)    Absorbency    ______________________________________     0            0.83    30            0.83    ______________________________________

EXAMPLE 15

Effect of stabilizers on the viscosity ink

A 1/16 inch hole is drilled in a Hewlett-Packard magenta ink cartridgeand a syringe is used to remove the ink. 2 equivalents of triiodophenoland 2 % wt/wt of ethyl hydroxy β-cyclodextrin are added to the inksample and thoroughly mixed. The admixture is then put back into thecartridge using the syringe. An HP 1200C printer is used and 20 to 30sheets are printed to get the cartridge to print fully. The viscosity iscompared to control (untreated) ink by placing it in a burette andmeasuring volume poured from the cartridge in 10 seconds. Each value isthe result of two pourings. The following table shows that the treatedink had approximately the same viscosity as the control ink.

    ______________________________________    Experiment      Control Additive    ______________________________________    1               6.4 g   6.3 g    2               5.4 g   5.3 g    3               6.0 g   6.4 g    ______________________________________

EXAMPLE 16

Fade test on ink from Example 15

The cartridge prepared in Example 15 is used to print on a transparency(Hewlett-Packard, Palo Alto, Calif., Cat. No. HPC 3834A) so that asquare inch of ink gives an absorbency reading of between 0.85 and 0.95.The square is then cut out and exposed to a fusion lamp having a watercooled Pyrex filter. The results of the test are shown in the followingtable:

    ______________________________________    Time     Treated (Absorbency                           Control (Absorbency)    ______________________________________     0       0.97          0.88    10       0.97          0.83    20       0.96          0.59    30       0.83          0.42    ______________________________________

EXAMPLE 17

Effect of triiodophenol and tetramethylammonium iodide on ink.

A hole is drilled in a Hewlett-Packard magenta ink cartridge (HewlettPackard, Palo Alto, Calif., Part No. HP 51640 M) and a syringe is usedto remove the ink. 2 equivalents of triiodophenol and 0.5 equivalents of(CH₃)₄ NI and 2% wt/wt of ethyl hydroxy β-cyclodextrin is added to theink sample and thoroughly mixed. The admixture is then put back into thecartridge using the syringe. The loaded cartridge is then placed in a HP1200C printer and 20 pages are printed to stabilize the cartridge.Squares are then printed on transparencies according to Example 16. Thesquares are then cut out and exposed to a fusion lamp having a watercooled Pyrex filter. The results of the test are shown in the followingtable:

    ______________________________________    Time         Treated   Control    (min)        (Absorbency                           (Absorbency)    ______________________________________     0           0.90      0.88    20           0.85      0.59    30           0.80      0.42    ______________________________________

No leakage or printing problems are observed and the cartridge is usedto print 205 pages with no problems.

EXAMPLE 18

Cartridges are prepared according to Example 15 and printed ontransparencies according to Example 16. The squares are exposed to xenonlamp radiation with a Pyrex/water filter. The UV absorption isdetermined at the indicated times. The results of the test are shown inthe following table:

    ______________________________________                 Treated   Control    Time         (Absorbency                           (Absorbency)    ______________________________________     0 hrs       1.13      0.93    23 hrs       1.06      0.61    44 hrs       1.03      0.42    ______________________________________

EXAMPLE 19

Examples of compounds that did not significantly stabilize dyes

Using protocols similar to those described in the previous examples, thefollowing compounds were tested for their ability to stabilize the dyesin ink jet inks: 2,4,6-triiodobenzoic acid, sodium salt, β-carotene,3,4-didehydroretinol (Vitamin A), ascorbic acid, 4-iodobenzoic acid,selenium EDTA complex and TINUVIN 936 (Ciba-Geigy Corporation). None ofthese representative compounds significantly stabilized any of the dyestested.

EXAMPLE 20

Representative combinations of colorant stabilizers

The following table represents various combinations of the desiredcolorant stabilizers that can be used to stabilize dyes. The particularcombination that will be used will depend upon the final formulation ofdye solution. The following table is not meant to be a comprehensiverepresentation of all possible combinations but is only meant to showseveral possible combinations.

    ______________________________________    NaI = sodium iodide (NI)    (CH.sub.3).sub.4 NI = tetramethylammonium iodide (TI)    CD = cyclodextrin (CD)    ______________________________________     ##STR35##     ##STR36##     ##STR37##     ##STR38##     ##STR39##     ##STR40##    ______________________________________    NI    (CH.sub.3).sub.4 NI                   BFI     BFI + BFI +  BFI + BFI +                           CD    TI     TI +  NI                                        CD    TIP   TIP -    TIP +   TIP + TIP +  TIP + BFI +          CD       NI      NI +  TI     TI +  NI +                           CD           CD    CD    ASA   ASA +    ASA +   ASI   ASI +  ASI + ASI +          TI       TI +          TI     CD    CD +                   CD                         TI    NaI + TI       TI +    ASI - ASI -  ASI -    CD             CD      CD    CD +   CD +                                 TI     NI    TIP + TIP -    TIP -   TIP -    CD    CD       CD +    CD +                   NI      TI    ASA + ASA +    ASA +    CD    NI       NI +                   CD    ______________________________________

EXAMPLE 21

Preparation of Tosyl Sugar

To a 500 ml round bottom flask fitted with a magnetic stirrer andcondenser is placed 75 g of 1,2-o-isopropylidene-D-glucofuranose(Aldrich) and 200 ml of anhydrous pyridine (Aldrich). The flask iscooled in an icebath and then 64.8 g of p-toluene sulfonyl chloride(Aldrich) is added. The mixture is stored overnight and allowed to warmto room temperature. The solvent is removed under reduced pressure, theoil redissolved in ether and washed with saturated copper sulfatesolution, dried with MgSO₄, and the solvent removed to yield a lightyellow viscous oil. The yield is 108.1 g (85%). The reaction issummarized as follows: ##STR41##

The resulting reaction product has the following reaction parameters:

1H NMR DMSO-d₆ ! 7.5-8.8 (m, Tosyl-Aromatic Hs), 1.2-1.6 (m, sugar'sketal CH₃ s)

EXAMPLE 22

Preparation of Trimethylphenol Sugar

To a 500 ml three-necked flask fitted with a magnetic stirrer, condenserand gas-inlet tube being continuously flushed with argon, 20.0 g of2,4,6-trimethylphenol (Aldrich) and 150 ml of dry tetrahydrofuran("THF") is placed into the flask. 4.2 g of sodium hydride is slowlyadded over 30 minutes and the gas evolution allowed to subside. Thereaction mixture is stirred for 30 minutes after which 55.1 g of thetosyl sugar prepared in Example 21 is added in 50 ml of THF. Thereaction mixture is stirred overnight and then refluxed for 60 minutes.The reaction mixture is then filtered and the solvent removed underreduced pressure to yield a brown oil The oil is then dissolved in 200ml of ether and 100 ml of 2N sodium hydroxide solution and the mixturestirred for one hour. The organic layer is then separated, dried withMgSO₄, and the solvent removed to yield a pale yellow oil. The yield is32.1 g (62%). The reaction is summarized as follows: ##STR42##

The resulting reaction product, (3aR, 6S, 6aR)-Tetrahydro-6-hydroxy-α-(mesityloxy)methyl!-2,2-dimethylfuro 2,3-d!-1,3-dioxole-5-methanol, hadthe following physical parameters:

1H NMR DMSO-d₆ ! key peaks: 7.3-6.8 (m), 4.8-3.7 (m), 2.2-2.5 (m),1.5-1.7 (m) ppm. Mass Spectrum: m/e: 338, 323, 281, 263, 265, 208, 203,178, 149, 136, 121, 91, 73, 69.

EXAMPLE 23

Removal of Ketal Group

To a three necked flask fitted with a gas inlet and outlet and magneticstirrer, is placed 20.0 g of the trimethylphenol sugar produced inExample 22 and 200 ml of anhydrous THF. Dry HCl gas (Matheson) isbubbled into the solution until the reaction mixture has a pH of 5-3 onmoist Universal Indicator paper. The reaction was stirred at roomtemperature for one hour and the solvent removed under reduced pressureto yield a light brown oil The oil was found to be highly water soluble.The reaction is summarized as follows: ##STR43##

The resulting reaction product, (2S, 3R, 4R)-Tetrahydro-5-1-hydroxy-2-(mesityloxy)ethyl!-2,3,4-furantriol, had the followingphysical parameters:

1H NMR DMSO-d₆ ! showed loss of ketal CH₃ groups at 1.5 to 1.7 ppm.

EXAMPLE 24

Preparation of Triiodophenol Sugar

Into a three-necked round bottom flask fitted with a magnetic stirrer,gas inlet, and condenser, is placed 20 g 2,4,6-triiodophenol and 200 mlof dry THF. The flask is cooled in an ice bath and 1.2 g of sodiumhydride added slowly over 30 minutes. The mixture is then stirred for 30minutes and then 15.6 g of tosyl sugar from Example 21 added in 50 ml ofTHF. The reaction is then heated to reflux overnight. The reactionmixture is then filtered and the solvent removed to yield a dark brownoil. The oil is then stirred in 200 ml of diethyl ether and 200 ml of 2Nsodium hydroxide. The organic layer is then separated, dried with MgSO₄,and the solvent removed under reduced pressure to yield a pale yellowoil. The yield is 21.3 g (76%). The reaction is summarized as follows:##STR44##

The resulting reaction product, (3aR, 6S,6aR)-Tetrahydro-6-hydroxy-2,2-dimethyl-α-(2,4,6-triiodophenoxy)methyl!furo 2,3-d!-1,3-dioxole-5-methanol, has thefollowing physical parameters:

Mass Spectrum: m/e: 529, 460, 431, 402, 358, 289, 275, 231, 145, 129,73.

EXAMPLE 25

Removal of Ketal Group

To a 250 ml three necked round bottom flask fitted with gas inlet andoutlet is placed 10.0 g of triiodophenol sugar produced in Example 24and 150 ml of anhydrous THF. Dry HCl gas is bubbled into the reactionmixture until the solution has a pH of 3-5 on moist Universal Indicatorpaper (Fisher). The reaction mixture is then evaporated under reducedpressure to yield 8.8 g (96%) of a pale yellow oil. The reaction issummarized as follows: ##STR45##

The resulting reaction product, (2S, 3R, 4R)-Tetrahydro-5-1-hydroxy-2-(2,4,6-triiodophenoxy)ethyl!-2,3,4-furantriol, has thefollowing physical properties:

Mass Spectrum: m/e: 529, 460, 347, 231, 145, 129, 73

EXAMPLE 26

Fade Testing of Hewlett Packard Magenta Ink with Additives Prepared inthe Examples Above on Neenah Bond Paper

Three Hewlett Packard HP5 1640M Magenta ink cartridges (Palo Alto,Calif.) are drilled with a 1/8 inch drill and the ink removed viasyringe into a 250 ml Erlenmeyer flask. 4.8 g (2% wt/wt) β-hydroxyethylcyclodextrin (American Maize) is added to the 96.7 g ink and the mixtureshaken for 10 minutes to dissolve and disperse the cyclodextrin. Then8.7 g trimethylphenol sugar (3 molar equivalents, or "eq") produced inExample 23, 19.3 g of triiodophenol sugar (4 eq) produced in Example 25,and 5.6 g of NaI (2 eq), are added to the mixture and shaken andsonicated for 20 minutes. The resultant mixture is then divided evenlyinto three aliquots, and one aliquot each of the resultant mixture isreintroduced into each of the drilled ink cartridges via syringe andfiltered simultaneously through a 0.45μ filter. The cartridges are thenplaced into a Hewlett Packard 1600C printer and test sheets are printedout on Neenah Bond, Kimberly Clark Corporation. Sheets number 30-32 aregenerated and subjected to fade studies against control sheets asdescribed above, except that the sheets are exposed to an Atlas ElectricDevices Co. (Chicago, Ill.) Weatherometer, Model No. C135W, radiance at0.53 watts/m² at 340 nm, wherein the black panel is at 32° C.,borosilicate filters, and the humidity is 50%. Absorbency is measuredafter 0 and 66 hours of exposure of the control and experimental samplesgenerated above. Absorbency is measured with a Perkin Elmer UV/VisibleSpectrophotometer λ14B.

The results of the fade studies are shown in the tables below. The tablebelow reports the fade study absorbancy results for the control sheetsamples at 0 and 66 hours.

    ______________________________________    CONTROL SHEETS    Absorbancy at 0 and 66 hours    Sample No.        T.sub.0                             T.sub.66    ______________________________________    1                 1.2    0.00    2                 1.2    0.10    3                 1.2    0.15    4                 1.2    0.14    5                 1.2    0.13    6                 1.18   0.15    ______________________________________

The table below reports the fade study absorbancy results for theexperimental sheet samples generated as described above at 0 and 66hours.

    ______________________________________    EXPERIMENTAL SHEETS    Absorbancy at 0 and 66 hours    Sample No.        T.sub.0                             T.sub.66    ______________________________________    1                 1.07   0.90    2                 1.10   0.85    3                 1.10   0.80    4                 1.05   0.85    5                 1.10   0.85    ______________________________________

EXAMPLE 27

Fade Testing of Hewlett Packard Magenta Ink on Transparency Sheets

The procedure of Example 26 is repeated except that the control andexperimental inks are printed on Hewlett Packard Premium TransparencyHPC 3834A sheets instead of on Neenah Bond paper. The control sheetabsorbancy values after 66 hours are 0.09 for sample 1, and 0.02 forsample 2. The experimental absorbancy value after 66 hours is 0.79 forsample 1.

EXAMPLE 28

Testing of Treated Paper for Reduction of Yellowing.

The yellowing of paper is tested by dipping the paper in a solution asdescribed below, drying the paper, and then exposing the paper in aweatherometer for 12 hours. More particularly, the paper is placed in acontainer to soak in the solution, hung on a line in a fumehood to dripdry, and then oven dried as described below.

Solution A Sodium Iodide+Sodium Thiosulfate

A 6.7% wt/wt sodium iodide and 10% wt/wt sodium thiosulfate solution inwater is prepared. Strips of Neenah bond paper are dipped into thesolution and then dried in a vacuum oven at 60° C. for 15 minutes. Thepaper is then placed into an Atlas Weatherometer and exposed to thefollowing conditions for twelve hours: 0.53 W/m², 50% humidity, 32° C.

Solution B Sodium Iodide

A 6.7% wt/wt solution of sodium iodide is prepared and Neenah bond paperstrips are dipped therein, dried, and exposed in a weatherometer asdescribed above.

Solution C Sodium Thiosulfate

A 10% wt/wt solution of sodium thiosulfate is prepared and Neenah bondpaper strips are dipped therein, dried, and exposed in a weatherometeras described above.

Control

Strips of Neenah bond paper were cut and exposed in a weatherometer asdescribed above.

The results of exposing the treated and control strips of paper are asfollows: The paper treated with solution A turned yellow. The papertreated with solution B turned dark yellow. The paper treated withsolution C did not change, and remained white. The control samplesturned very pale yellow. Accordingly, treating paper with sodiumthiosulfate reduces the amount of yellowing that occurs over time.

EXAMPLE 29

Fade Testing of Hewlett Packard Inks Printed on Sodium ThiosulfateTreated Paper

This example determines if sodium thiosulfate treated paper enhances theresistance to fade of Hewlett Packard Ink admixed with the colorantstabilizers of the present invention.

Several sheets of Hewlett Packard premium ink jet paper are soaked in a10% wt/wt aqueous solution of sodium thiosulfate, and then dried in avacuum oven at 60° C. for 15 minutes at 0.1 mm Hg. These sheets arereferred to as the "treated paper".

The Hewlett Packard ink cartridge (magenta ink) is prepared as describedabove, by drilling a hole in the cartridge, removing the ink via asyringe, and placing the ink in an Erlenmeyer flask. 5% wt/wt ofhydroxyethyl-β-cyclodextrin is put into the flask, and the mixtureshaken for 10 minutes. Afterwards, 3 equivalents of triiodophenol sugarproduced in Example 25, 4 equivalents of trimethylphenol sugar producedin Example 23, and 2 equivalents of sodium iodide are added to themixture and shaken for 20 minutes. It is to be understood that"equivalents" above are molar equivalents to the dye in the ink. The Inkmixture is then reinjected into the ink jet cartridge via syringe with0.45μ filter attachment. This cartridge is referred to as the additivecontaining cartridge.

Test sheets are printed using control cartridges (other Hewlett Packardink jet cartridges, including magenta, yellow, and cyan, without theabove additives) and the additive containing cartridge on treated anduntreated paper. More particularly, treated and untreated sheets areprinted with Hewlett Packard magenta, yellow, and cyan ink cartridgesthat do not contain additives. Additionally, treated and untreatedsheets are printed with Hewlett Packard yellow and cyan ink cartridgesthat do no contain additives and with the additive containing cartridgethat contains magenta ink. The paper is then placed in the AtlasWeatherometer and exposed for 15 hours to the following conditions: 0.53W/m² at 340 nm, 50% humidity, borosilicate filters, and 32° C.

The change in color is measured by the Xrite Colorimeter (Model 938,SpectroDensitometer, Grandville, Mich.) which measures the ΔE* values,based on the L, a*, b* as described by Cielab, D-50-2.

Visual and actual measurements show the control magenta ink on untreatedpaper faded the most, the additive-containing magenta ink on untreatedpaper faded less, and the additive-containing magenta ink on treatedpaper barely faded at all, and faded the least. More particularly, theΔE* values are as follows:

    ______________________________________    Paper         Magenta Ink                            ΔE* Values    ______________________________________    Untreated     Control   34.24    Untreated     Additives 20.53    Treated       Additives 11.09    ______________________________________

Percentage wise, additive containing ink is 40% better in faderesistance than control ink (both on untreated paper), and additivecontaining ink on treated paper is 68% better in fade resistance thancontrol ink on untreated paper, after 15 hours exposure.

Examination of the % Reflectance graphs of the samples before and afterfading shows that the magenta dye does not fade or its concentrationchange when the additive is present in the ink and it is printed on thetreated paper. However, the control clearly shows loss of the dyechromophore. In contrast, the additive system in the ink protects theloss of dye, however the ΔE* values show that the additive systemyellows somewhat upon exposure to light, hence yielding the ΔE* value.The treated paper therefore decreases this yellowing of the additivethus giving the smallest ΔE* (color change) after 15 hours of exposure.

EXAMPLE 30

Fade Testing of Yellow Hewlett Packard Inks Printed on SodiumThiosulfate Treated Paper and Untreated Paper

This example determines if sodium thiosulfate treated paper enhances theresistance to fade of yellow Hewlett Packard Ink.

The papers exposed to the Atlas Weatherometer in Example 29 also hadyellow and cyan squares printed thereon in boxes next to the magentasquares. Although some of the magenta squares contained the stabilizingadditives, all of the yellow and cyan squares did not contain theadditives.

Accordingly, yellow Hewlett Packard Ink is printed on both treated anduntreated Hewlett Packard premium ink jet paper and then exposed to theAtlas Weatherometer under the conditions listed in Example 29. It is tobe understood that the treated paper is soaked in a 10% wt/wt solutionof sodium thiosulfate and dried in a vacuum oven under the conditionslisted in Example 29.

The yellow ink on the weatherometer-exposed treated paper has little orno fading in comparison with the yellow ink on the unexposed treatedpaper. However, the yellow ink on the weatherometer-exposed untreatedpaper is substantially faded in comparison with the yellow ink on theunexposed untreated paper. Accordingly, the treated paper reduces thefade of the yellow ink in comparison to the untreated paper.

EXAMPLE 31

Fade Testing of Yellow Hewlett Packard Inks Printed on SodiumThiosulfate Treated Paper and Untreated Paper

This example determines if sodium thiosulfate treated paper enhances theresistance to fade of yellow Hewlett Packard Ink.

Additional ink samples were printed of Hewlett Packard inks, includingyellow ink, on treated and untreated paper using the method described inExample 29. The samples were placed in the Atlas Weatherometer under theconditions listed in Example 29, except that the samples were exposedfor a total of 51 hours.

Visual and color measurements (ΔE*) show that the treated paper reducesthe fade of the yellow ink. More particularly, the ΔE* values for theyellow ink are as follows:

    ______________________________________                   ΔE* Values for                               ΔE* Values for    Hours of Exposure                   Untreated Paper                               Treated Paper    ______________________________________    24             28.33       2.29    51             54.96       12.08    ______________________________________

The ΔE* values indicate little or no color change of the yellow ink onthe treated paper over 51 hours.

EXAMPLE 32

Fade Testing of Cyan Hewlett Packard Inks Printed on Sodium ThiosulfateTreated Paper and Untreated Paper

Samples were printed of Hewlett Packard inks, including cyan ink, ontreated and untreated paper using the method described in Example 29. Itis to be understood that none of the cyan inks contained the stabilizingadditives listed in Example 29. The samples were placed in the AtlasWeatherometer under the conditions listed in Example 29, except that thesamples were exposed for a total of 51 hours.

The treated paper had little or no effect on the fade of the HewlettPackard cyan ink in comparison to the untreated paper. At 24 hours and51 hours of total exposure to the Weatherometer, the cyan ink faded to asimilar extent on the treated and untreated paper.

EXAMPLE 33

Fade Testing Of Inks Printed On Treated Paper

Fade testing of a magenta American Ink Jet ink jet formulation for aCanon printer is conducted as follows. The magenta ink is printed oncyclodextrin treated paper and sodium thiosulfate treated paper, andthen exposed for 100 hours in an Atlas Weatherometer.

More particularly, approximately 10 ml of ink is removed from a smallcartridge for a Canon BJC printer by use of a syringe with needle, viathe wick plug. The following stabilizing additives are admixed with themagenta ink: 5% wt/wt of basic fuschin imine adduct prepared in Example7; 0.25 eq tetramethylammonium iodide; and 2% wt/wthydroxyethyl-γ-cyclodextrin. The ink admixture is placed back into thecartridge via syringe with a 0.45μ filter. The first 15 to 20 sheetsprinted are discarded to ensure that the ink admixture is being printedon the paper to be exposed to the Atlas Weatherometer.

Sodium Thiosulfate Treated Paper

The sodium thiosulfate treated paper is prepared as follows. A stocksolution of 15 g sodium thiosulfate is placed in a beaker of 150 g ofwater and dissolved. The solution is placed in a Pyrex oven dish andsheets of Hewlett Packard Premium ink jet paper are placed therein, onesheet at a time. After the sheet has soaked in the sodium thiosulfatesolution for 3 to 4 minutes, the sheets are removed and placed in avacuum oven which is heated to 30°-32° C. and the vacuum of 0.1 torrapplied for 15 to 20 minutes, producing dried sheets of paper.

By weighing a sheet before submersion in the sodium thiosulfatesolution, and after the drying step, the amount of sodium thiosulfatepresent on or in the paper is calculated to be approximately 12% wt/wt.

Cyclodextrin Treated Paper

The cyclodextrin treated paper is prepared as follows. A 10% wt/wtsolution of hydroxyethyl-γ-cyclodextrin is prepared, and sheets ofHewlett Packard Premium ink jet paper are treated as described above. Byweighing a sheet before submersion in the cyclodextrin solution, andafter the drying step, the amount of cyclodextrin present on or in thepaper is calculated as approximately 3.4%.

A series of sheets are printed on the Canon BJC printer using the inkadmixture prepared above or the commercially available ink for theprinter as the control. Untreated sheets are printed (control), as wellas sodium thiosulfate treated sheets and cyclodextrin treated sheets.The sheets are then exposed to light radiation for 100 hours in an AtlasWeatherometer having the following conditions: 0.54 W/m² at 440 nmirradiance; black panel temperature of 45° C.; borosilicate filters; andhumidity of 55%. The color change readings (ΔE*) are measured using theX-rite meter. The results are reported below.

    ______________________________________    Sample                ΔE*                                 ΔH*    ______________________________________    Control ink on untreated paper                          47.6   -3.1    Ink admixture on untreated paper                          15.7   15.3    Ink admixture on cyclodextrin paper                          5.9    0.6    Ink admixture on thiosulfate paper                          9.3    2.8    ______________________________________

As can be seen above, the stabilizing molecules in the ink admixtureimprove the light fastness and give a slight shift in hue of thecolorant therein upon exposure to radiation. However, the above dataclearly shows that the stabilizing molecules in the ink, in combinationwith the ink being printed on the treated paper, significantly improvesthe colorants resistance to fade upon exposure to radiation. Thecyclodextrin treated paper gave the colorant the greatest improvement inlight fastness, with the sodium thiosulfate treated paper giving thecolorant the second best improvement in light fastness.

EXAMPLE 34

Preparation of Treated Paper

This examples describes one method of treating paper with eithercyclodextrin or sodium thiosulfate. Hewlett-Packard premium ink jetpaper is coated and dried to obtain flat treated paper for ink jet fadestudies described in Examples 35 and 36.

More particularly, the paper is coated as follows. The paper is rolledbetween two rollers that are positioned on top of each other, whereinthe bottom portion of the bottom roller is submersed in a solution ofeither cyclodextrin or sodium thiosulfate, and wherein a controlledamount of the same solution is continually dripped onto the top portionof the top roller. It is to be understood that as the paper rollsbetween the rollers, the paper is coated on its top surface by contactwith the lower portion of the top roller which contains the solutionthereon, and the solution continues to be applied to the top portion ofthe top roller as it rolls via contact with the paper. Additionally, asthe paper rolls between the rollers, the paper is coated on its bottomsurface by contact with the top portion of the bottom roller whichcontains the solution thereon, and the solution continues to be appliedto the lower portion of the bottom roller (which is submersed in thesolution) as it rolls via contact with the paper.

After the paper passes through the rollers as described above, it isrolled onto a steel, steam heated drum with a fabric flap to prevent thepaper from curling as it is dried thereon.

The γ-cyclodextrin treated paper is prepared as follows. The HP premiumpaper is weighed prior to treatment. A 50% by weight aqueous solution ofγ-cyclodextrin is prepared and applied to the top and bottom surfaces ofthe HP premium paper as described above. After the treated paper isdried, the paper is again weighed to yield a 7% wt/wt cyclodextrincontent in or on the paper.

The sodium thiosulfate treated paper is prepared as follows. The HPpremium paper is weighed prior to treatment. A 20% by weight aqueoussolution of sodium thiosulfate is prepared and applied to the top andbottom surfaces of the paper as described above. After the treated paperis dried, the paper is again weighed to yield a 2% wt/wt sodiumthiosulfate content on or in the paper.

These treated papers are used in the fade testing studies reported inExamples 35 and 36.

EXAMPLE 35

Fade Testing of Various Magenta Inks on Treated Paper

This example reports the results of fade testing of Hewlett-Packard(HP), American Ink Jet (AIJ), and Canon magenta ink jet inks, eitherwith or without the stabilizing additives of the present invention, ontreated or untreated Hewlett-Packard Premium paper.

The inks having the stabilizing additives of the present invention areprepared as described in the above examples, wherein the ink is removedfrom the appropriate cartridge, mixed with the additives, shaken andthen sonicated for 20 minutes, then injected into the original cartridgevia syringe fitted with a 0.45μ filter. The resultant ink contains thefollowing additives: 5% wt/wt of the basic fuschin imine adduct preparedin Example 7; 0.25 eq of tetramethylammonium iodide; and 2% wt/wthydroxyethyl β-cyclodextrin.

The magenta inks are printed onto HP premium paper and the treated paperprepared in Example 34. The Hewlett-Packard inks and the American InkJet inks are printed using a Hewlett-Packard 1600C printer and the Canoninks are printed using a BJC-600 printer.

The sheets were then placed in the Atlas Weatherometer and exposed for atotal of 77 hours under the following conditions: 0.54 W/m² at 440 nm,borosilicate filters, 55% humidity, and 45° C. black panel temperature.

The change in color of the magenta ink is measured by the XriteColorimeter (Model 938, SpectroDensitometer, Grandville, Mich.) whichmeasures the ΔE* values, based on the L, a*, b* as described by Cielab,D-50-2. The results are reported in the table below.

    ______________________________________                   ΔE* Values                     24     45       63   77    Samples          Hrs.   Hrs.     Hrs. Hrs.    ______________________________________    HP Ink on HP Paper                     12.5   24.6     41.1 64.0    HP Ink on CD Treated                     9.1    13.3     20.0 31.5    Paper    HP Ink + Additives on HP                     5.3    9.9      17.1 25.0    Paper    HP Ink + Additives on CD                     7.4    9.9      12.3 14.7    Paper    AIJ Ink on HP Paper                     6.3    12.1     22.0 37.0    AIJ Ink on CD Treated                     2.7    4.3      8.0  13.7    Paper    AIJ Ink + Additives on CD                     1.2    1.6      1.7  3.5    Paper    Canon Ink on HP Paper                     5.6    6.0      7.0  9.0    Canon Ink + Additives on                     1.6    1.8      2.0  2.4    Thiosulfate Treated Paper    ______________________________________

As shown above, the additives reduce fade, and when the ink containingthe additives is printed on treated paper, the amount of fade is evenfurther reduced.

EXAMPLE 36

Fade Testing of Various Magenta Inks on Treated Paper

This example reports the results of fade testing of Hewlett-Packard(HP), American Ink Jet (AIJ), and Canon magenta ink jet inks, eitherwith or without the stabilizing additives of the present invention, ontreated or untreated paper. More particularly, the paper is untreatedHewlett-Packard Premium paper, Kimberly-Clark Bright White ink jetpaper, or Hewlett-Packard Premium paper treated as described in Example34. Three types of treated paper are prepared using one of the followingthree aqueous solutions: 50% wt/wt γ-cyclodextrin; 20% wt/wt sodiumthiosulfate; or 20% wt/wt γ-cyclodextrin and 10% wt/wt sodiumthiosulfate.

As stated above in Example 34, the 50% cyclodextrin treated paper has a7% wt/wt cyclodextrin content in or on the paper, and the 20% sodiumthiosulfate treated paper has a 2% wt/wt sodium thiosulfate content inor on the paper. The paper treated with the 20% wt/wt y-cyclodextrin and10% wt/wt sodium thiosulfate solution is weighed before and aftertreatment, to yield a 4 to 5% wt/wt total content of cyclodextrin andsodium thiosulfate in or on the paper.

The treated and untreated paper is printed with the additive containinginks prepared in Example 35 or with the corresponding non-additivecontaining inks. The HP and AIJ inks were printed from HP 1600cartridges using an HP 1600C printer. The Canon ink was printed with aBJC-600 printer.

The sheets were then placed in the Atlas Weatherometer and exposed for atotal of 77 hours under the following conditions: 0.54 W/m² at 440 nm,55% humidity, 45° C. black panel temperature, borosilicate filters.

The change in magenta color is measured by the Xrite Colorimeter (Model938, SpectroDensitometer, Grandville, Mich.) which measures the ΔE*values, based on the L, a*, b* as described by Cielab, D-50-2. Theresults are reported in the table below.

    ______________________________________                       Values at 77 Hours    Paper                ΔE*                                ΔH*    ______________________________________    HP Inks With Additives    Hewlett-Packard Paper                         25.0   13.3    50% Cyclodextrin     14.7   9.0    20% Cyclodextrin/10% 15.7   8.0    Thiosulfate    20% Thiosulfate      20.4   12.2    Kimberly-Clark Bright White                         16.0   --    HP Inks (No Additives)    Hewlett-Packard Paper                         64.0   11.3    50% Cyclodextrin     31.5   10.5    20% Cyclodextrin/10% 21.0   10.3    Thiosulfate    20% Thiosulfate      27.2   13.6    Kimberly-Clark Bright White                         32.5   10.8    AIJ Inks With Additives    Hewlett-Packard Paper                         11.8   0.12    50% Cyclodextrin     3.5    0.1    20% Cyclodextrin/10% 10.0   1.9    Thiosulfate    20% Thiosulfate      11.4   1.5    Kimberly-Clark Bright White                         8.0    2.0    AIJ Inks (No Additives)    Hewlett-Packard Paper                         37.0   -3.11    50% Cyclodextrin     13.7   -3.7    20% CD/10% Thiosulfate                         21.2   16.6    20% Thiosulfate      5.6    4.0    Kimberly-Clark Bright White                         13.8   -0.47    Canon Inks With    Additives    Hewlett-Packard Paper                         8.2    2.7    50% Cyclodextrin     4.3    3.2    20% Cyclodextrin/10% 2.4    1.3    Thiosulfate    20% Thiosulfate      2.4    0.01    Kimberly-Clark Bright White                         7.0    --    Canon Inks (No    Additives)    HP Paper             9.0    2.0    20% Thiosulfate      2.4    0.1    ______________________________________

EXAMPLE 37

Preparation of Heat Sealable Media Products Containing ColorantStabilizer Additives

This example describes the preparation of heat sealable media productscontaining colorant stabilizing additives of the present invention. Inthis example, the colorant stabilizing additive is a molecularincludant, such as hydroxypropyl β-cyclodextrin. Heat sealable mediaproducts provide many uses. For example, such a media product can beconstructed of a substrate layer such as paper, coated with at least onepolymer containing the colorant stabilizing additive of the presentinvention. These media products can be used as an alternative tolaminating products, in order to provide a lightfast and waterfast mediaproduct.

Additionally, such media products can be heat transfer products asdescribed for example in U.S. Pat. No. 4,863,781, U.S. Pat. No.5,242,739 and U.S. Pat. No. 5,501,902, which are hereby incorporated byreference. Generally, heat transfer products comprise a substrate layer,such as paper, coated with at least one polymer which releases aprintable material upon the application of pressure and heat. Such heattransfer products are commonly used for melt printing designs onarticles of clothing, for example. Additionally, heat transfer papershave been developed specifically for transferring graphics printed withan ink jet printer.

The thermoplastic polymers coating one or both sides of the substratelayer are typically selected from polyolefins, polyesters,ethylene-vinyl acetate copolymers or nylons. Additional componentsinclude humectants, ink viscosity modifiers, weak acids, surfactants,and binders, for example.

The present invention provides that from about 2% to 20% wt/wt molecularincludant may be added to the coating polymer as a colorant stabilizingadditive. The example below describes the production of two such mediaproduct coatings. The following ingredients were combined to makecoating Formula A:

1) 217 parts water

2) 35 parts styrene maleic anhydride

3) 4.4 parts 28% solution ammonia in water

4) 88 parts 25% solution ethylene acrylic acid (available as MICAM PRIMEfrom Michaelman Inc.)

5) 88 parts nylon copolymer 6/12, (available as ORGOSOL from ElfAtachem) having the formula

6) 88 parts polyvinyl alcohol

7) 38 parts 30% solution hydroxypropyl β-CD

All ingredients were combined in a beaker, and blended with a mechanicalstirrer into a smooth white paste. The paste was then milled for furtherconsistency.

Suitable variations of the above formula will be apparent to thoseskilled in the art through routine experimentation. For example, in onealternative formulation, coating Formula B, elements 1-6 were combinedin the same proportions, however, 456 parts 30% solution hydroxypropylβ-CD was used instead of 38 parts. As can be seen in the results below,the higher molecular includant content Formula B coating produced a morefade resistant media product. The results support a range of colorantstabilizer additive amounts.

The media coatings were then separately applied to a substrate, HPpremium paper, by drawing down with a zero draw down bar. The wetcoating was then dried in a vacuum oven to produce a coated mediaproduct. Ink B3, prepared as described below, was then printed onto thesamples. The ink was fused to the media coating by briefly heating atabout 300 degrees Fahrenheit for about 30 seconds.

When vinyl is used as an underlying coating layer, such as in a heattransfer product, the coating can be preferably adhered thereto by theaddition of an intermediate coating layer, such as 50% wt of a polyvinylacetate and silica, mill ground for consistency.

Printed sheets of media product from this example were placed in theAtlas weatherometer and exposed for the designated number of hours underthe following conditions: 0.54 W/m² at 440 nm, 55% humidity, 45° C.black panel temperature, borosilicate filters.

The change in magenta color is measured by the Xrite Colorimeter (Model938, SpectroDensitometer, Grandville, Mich.) which measures the ΔE*values, based on the L, a*, b* as described by Cielab, D-50-2. Theresults are reported in the tables below.

    ______________________________________    B3 Ink       DI Water    85.11%                 2 Pyrrolidone                             10.00                 Giv Guard DXN                             00.20                 Cobratec 99 00.10                 Triethanolamine                             00.50                 Reactive Red 120                             2.89                 Acid Red 52 1.20    ______________________________________

    ______________________________________    Fade Testing Results of Coated Media Products                      21 Hour    Sample              ΔE*                               ΔH*    ______________________________________    B3 Ink on Formula A 3.2    -3.7    Coated Paper    B3 Ink on Formula B 0.85   0.07    Coated Paper    B3 on Control Paper 3.7    3.2    ______________________________________

EXAMPLE 38

Preparation and Testing of Inks Containing Porphine Colorant Stabilizers

This example reports the results of fade testing of various inks, eitherwith or without the stabilizing additives of the present invention, ontreated or untreated paper. More particularly, the paper is untreatedHewlett-Packard premium paper, or treated Hewlett-Packard premium paperprepared using a solution of about 50% wt/wt hydroxypropylγ-cyclodextrin to ink, in or on the paper in a concentration of about 5to 15% wt/wt solution to paper.

The stabilizing additives of this example can be porphines.Specifically, the porphines Cu-meso-tetra-(4-sulfanatophenyl)-porphine(designated CuTPPS4) and Cu-meso-tetra-(N-methyl-4-pyridyl)-porphine(designated CuTMPS4) (available from Porphyrin Products, Inc., Logan,Utah) were used, which are represented by the following structures,respectively: ##STR46##

The invention provides that the metal ion Co or Cu may be usedinterchangeably in the porphine structures of the present invention.Additional background on the chemistry of porphines can be found inKubat et al. "Photophysical properties of metal complexes ofmeso-tetrakis (4-sulphonatophenyl) Porphyrin," Journal of Photochemistryand Photobiology A:Chemistry 96 (1996) 93-97, and references citedtherein, hereby incorporated by reference.

The stabilizing additive of this example can also optionally be dimethylamino benzoic acid quat (designated DMABAQ), which can be produced asshown in the following reaction. ##STR47##

Into a 3 necked 500 ml. round bottomed flask fitted with magneticstirrer and condenser was added 20 g (0.12 moles) dimethyl amino benzoicacid (Aldrich) and 100 ml. of toluene. The Dean-Stark adapter was fittedand 80 ml. of toluene (Aldrich anhydrous grade) 14.4 g (0.12 mole)thionyl chloride added and the mixture heated at reflux for 2 hours.Toluene was then distilled off as more (100 ml.) was added. 16.8 g (0.12mole) of choline chloride (Aldrich) dried in 50 ml. of toluene (DeanStark) was added and the mixture refluxed overnight. The solution wasthen filtered hot and poured into a beaker chilled in an ice bath. TheDMABAQ solid was then filtered and dried in a vacuum oven at 30°overnight.

Printed sheets of paper were placed in the Atlas weatherometer andexposed for the designated number of hours under the followingconditions: 0.54 W/m² at 440 nm, 55% humidity, 45° C. black paneltemperature, borosilicate filters.

The change in magenta color is measured by the Xrite Colorimeter (Model938, SpectroDensitometer, Grandville, Mich.) which measures the ΔE*values, based on the L, a*, b* as described by Cielab, D-50-2. Theresults are reported in the tables below.

The treated and untreated paper is printed with inks designated A1, A2,A3, A4, B1, B2, B3, B4, C1, C2, C3, and C4, prepared as follows:

    ______________________________________    A1 Ink       DI Water     84.80%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              4.00                 Acid Red 52  0.40    A2 Ink       DI Water     85.40%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              3.00                 Acid Red 52  0.80    A3 Ink       DI Water     86.00%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              2.00                 Acid Red 52  1.20    A4 Ink       DI Water     86.60%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              1.00                 Acid Red 52  1.60    B1 Ink       DI Water     83.02%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              5.78                 Acid Red 52  0.40    B2 Ink       DI Water     84.07%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              4.33                 Acid Red 52  0.80    B3 Ink       DI Water     85.11%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              2.89                 Acid Red 52  1.20    B4 Ink       DI Water     86.16%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              1.44                 Acid Red 52  1.60    C1 Ink       DI Water     82.62%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              6.18                 Acid Red 52  0.40    C2 Ink       DI Water     82.62%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              4.63                 Acid Red 52  0.80    C3 Ink       DI Water     84.91%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              3.09                 Acid Red 52  1.20    C4 Ink       DI Water     86.06%                 2 Pyrrolidone                              10.00                 Giv Guard DXN                              00.20                 Cobratec 99  00.10                 Triethanolamine                              00.50                 Reactive Red 120                              1.54                 Acid Red 52  1.60    ______________________________________

The above inks were fade tested with the following results.

    ______________________________________    Inks Without Additives                   63H    Ink ID #         ΔE*                            ΔH*    ______________________________________    A1               47.8   7.5    A2               57.5   21.6    A3               60.7   33.8    A4               62.1   43.2    B1               38     -0.54    B2               46.4   14.8    B3               56.3   28.4    B4               64.7   39.1    C1               69.4   2.6    C2               64.3   11.3    C3               72.4   20.5    C4               83.9   22.7    ______________________________________

The A2 ink was prepared with additives as described below and fadetested on HP paper and HP γ-CD paper with the following results.

    ______________________________________    A2 Inks                     15 h     78 h                     ΔE*                          ΔH*                                  ΔE*                                         ΔH*    ______________________________________    HP Paper    50% DMABAQ         65.3   24.4    50% DMABAQ         62.1   26.5    77.1 21.5    0.5% CuTPPS4 + 0.5% DMABAQ                       33.2   20.9    40.9 23.1    0.5% CuTPPS4 + 0.1% DMABAQ                       34.1   20.5    42.6 22.2    HP γ-CD Paper    50% DMABAQ         4.1    2.4     4.9  2    50% DMABAQ         6.3    4.5     7.7  5    0.5% CuTPPS4 + 0.5% DMABAQ                       4.2    -2.1    5.2  -2.5    0.5% CuTPPS4 + 0.1% DMABAQ                       3.5    -0.34   5.4  -3.1    ______________________________________

The A3 ink was prepared with additives as described below and fadetested on HP paper and HP γ-CD paper with the following results.

    ______________________________________    B3 Inks                     15 h     78 h                     ΔE*                          ΔH*                                  ΔE*                                         ΔH*    ______________________________________    HP Paper    50% DMABAQ         59.8   28.2    75.8 26.6    0.5% CuTPPS4 + 0.5% DMABAQ                       36.2   26.4    43.8 28.5    0.5% CuTPPS4 + 0.1% DMABAQ                       43.3   28.1    52.5 30.3    HP γ-CD Paper    50% DMABAQ         6.1    4.9     7.6  5.5    50% DMABAQ         10.4   8.4     12.4 9.7    0.5% CuTPPS4 + 0.5% DMABAQ                       6      -2.9    7    -3.2    0.5% CuTPPS4 + 0.1% DMABAQ                       4.1    -0.69   6.1  -2.1    ______________________________________

The inks were prepared with about 0.5% CuTPPS₄ stabilizing additive andfade tested on HP paper and HP γ-CD paper with the following results.

    ______________________________________    Inks made with 0.5% CuTPPS.sub.4 on HP premium paper    Samples 15 H             78 H        94 H    ID #    ΔE*                   ΔH* ΔE*                                  ΔH*                                         ΔE*                                              ΔH*    ______________________________________    A1      9.6    4.8       34.7 12.1   41.6 12.8    A2      14.7   12.8      41.8 23.8   48.8 24.9    A3      19.6   18.7      42.7 31.9   47   32.7    A4      29.6   28.9      51.8 42.4   55.5 42.1    B1      8.2    1.8       30.6 8.8    38.2 9.2    B2      8.3    6.3       32.3 17.8   37.8 18.8    B3      14.9   13.8      39.0 27.5   44.5 28.6    B4      25.2   24.6      47.7 38.3   51.6 38.5    C1      14.3   -7.71     41.8 8.9    N/A  N/A    C2      7.9    -2.7      33.7 13.9   N/A  N/A    C3      9.2    6.9       37.9 23.6   N/A  N/A    C4      23.1   22.2      48.6 37.7   N/A  N/A    ______________________________________

    ______________________________________    Inks with 0.5% CuTPPS.sub.4 on Hydroxy-Propyl γ-CD paper    Samples           15 H             78 H         94 H    ID #   ΔE*                  ΔH* ΔE*                                 ΔH*                                         ΔE*                                              ΔH*    ______________________________________    A1     1.5    -0.2      6.6  -3.2    8    -4.1    A2     1.2    0.28      4.1  -0.8    5.4  -1.3    A3     2.8    2.14      5    4.3     5.2  4.3    A4     4.9    4.7       10.4 9.8     10.2 9.5    B1     3.1    -1.5      9.4  -5.5    11.2 -6.9    B2     2.3    -2.4      7.7  -5.2    8.3  -5.7    B3     1.2    1.1       4.1  0.13    4.7  -0.79    B4     2.9    2.6       7.2  6.3     7.7  6.5    C1     4      -3.3      17.1 -13.8   N/A  N/A    C2     3      -2.6      3.4  -2.8    N/A  N/A    C3     1.6    -1.5      5.2  -3.3    N/A  N/A    C4     1.4    1.1       4.7  3.5     N/A  N/A    ______________________________________

Additionally, HP-1600 magenta ink was prepared with about 0.5% CuTPPS₄stabilizing additive and fade tested on HP paper and HP γ-CD paper withthe following results.

    ______________________________________    15 Hour Multiple Samples    Samples ID #     ΔE*                            ΔH*    ______________________________________    HP #1            14.68  13.13    HP #2            20.86  19.50    HP #3            17.01  15.55    HP #4            13.04  11.15    HP #5            13.11  10.57    HP #6            13.09  11.10    HP γ-CD #1 2.66   -1.47    HP γ-CD #2 1.20   -.53    HP γ-CD #3 2.44   -.53    HP γ-CD #4 1.30   -.47    HP γ-CD #5 1.74   -.30    HP γ-CD #6 1.35   -.34    ______________________________________

The HP-1600 magenta ink was also prepared with about 0.5% CuTMPS₄stabilizing additive and fade tested on HP paper and HP γ-CD paper withthe following results.

    ______________________________________    15 Hour Multiple Samples    ______________________________________    HP #1            13.94  11.39    HP #2            13.58  11.11    HP #3            13.98  11.57    HP #4            14.16  11.56    HP γ-CD #1 2.32   -.99    HP γ-CD #2 1.44   -1.05    HP γ-CD #3 2.17   -.67    HP γ-CD #4 1.98   -1.21    HP γ-CD #5 2.14   -1.38    HP γ-CD #6 1.79   -.85    HP γ-CD #7 .36    .15    ______________________________________

EXAMPLE 39

Preparation and Testing of Inks Containing Porphine and LanthanideColorant Stabilizers

This example reports the results of fade testing of various inks, eitherwith or without the stabilizing additives of the present invention, onuntreated paper. More particularly, the paper is untreated QIS PhotoGlossy paper.

The stabilizing additives of this example are porphines and europiumsalts. Specifically, the porphineCu-meso-tetra-(4-sulfanatophenyl)-porphine (designated CuTPPS4)(available from Porphyrin Products, Inc., Logan, Utah) is used, as inExample 38 above. The europium salt, europium nitrate (designated EuN)(Strem Chemical Co., Newburyport, Mass.) is used.

A forty-eight hour accelerated fade test of various magenta inkcomposition was performed. A magenta control without stabilizingadditives was applied to the QIS paper medium. After subjecting the inkcomposition and paper medium to the forty-eight hour test, ΔE* and ΔH*values were measured. Similar measurements were taken using thefollowing ink formulations:

a) magenta+0.5 wt. % CuTPPS4

b) magenta+0.05 wt. % EuN

c) magenta+0.5 wt. % CuTPPS4+0.05 wt. % EuN.

The resulting measurements are given below.

    ______________________________________    Ink Formulation                   Media         ΔE*                                        ΔH*    ______________________________________    Magenta Control                   QIS Photo Glossy                                 31.8   24.5    Magenta + CuTPPS4                   QIS Photo Glossy                                 16.4   -3.7    Magenta + EuN  QIS Photo Glossy                                 19.6   17.3    Magenta + CuTPPS4 +                   QIS Photo Glossy                                 7.8    2.8    EuN    ______________________________________

EXAMPLE 40

Preparation of Basic Fuschin Hydrazone

Another colorant stabilizer of the present invention is a basic fuschinhydrazone, prepared as follows. To a 500 ml round bottom flask, fittedwith a magnetic stirrer and a heating mantle, was placed 50 g (0.46mole) phenyl hydrazine (Aldrich), 96.3 g (0.46 mole) chalcone (Aldrich),and 300 ml. of anhydrous ethanol. The reaction mixture refluxedovernight and then cooled to room temperature. A white precipitateformed and was filtered to yield a white solid which was washed withcold ether. 128 g (93%) chalcone hydrazone was obtained. This reactionis shown below. ##STR48##

To a 500 ml three necked flask fitted with a condenser, Argon bubblesand a magnetic stirrer, was placed 20 g (0.09 mole) 4,4'-diaminobenzophenone (Aldrich), 27.1 g (0.09 mole) chalcone hydrazone (producedabove), 10.1 g phosphorous oxy chloride (Aldrich) and 200 ml of drieddioxane. The mixture was refluxed for two days to yield a red solution.The reaction mixture was chilled in an ice bath and the red precipitatefiltered to yield 35.2 g (78%). Addition of hexane to the solutiongenerated an extra 3 g The compound was purified by neutralization from3% ethanol in 97.1% chloroform. It was also run down a column (silicagel) with 1% ethanol in CHCl₃ to elute impurities, then the product waseluted with 10% ethanol in chloroform. This reaction is shown below.##STR49##

EXAMPLE 41

Preparation and Testing of Inks on Paper Containing BenzophenoneColorant Stabilizer Additives

This example reports the results of fade testing of magenta ink jet inkson Hewlett-Packard premium paper containing another stabilizingadditives of the present invention. In particular, the additive of thisexample is a benzophenone, of the general formula: ##STR50## wherein Rrepresents any substituents which permit the benzophenone to function asa colorant stabilizer.

More specifically, in this example the benzophenone derivative is2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid (designated HMBPD, orsimply U) (available from Lancaster Synthesis Ltd., Windham, N.H.),represented by the following structure: ##STR51##

In addition, the colorant stabilizing additive can be a molecularincludant, such as a cyclodextrin. The paper containing the additiveswas prepared as follows:

Pre-complexation of Additive U with 13-CD

5.0 g (0.02 mole) of 2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid(additive U), 27.2 g (0.02 mole) β-cyclodextrin and 136 ml water wasplaced in a beaker and stirred on a hot-plate stirrer. The suspensionwas heated to 65° C. at which point the mixture became a clear solution.

Paper Coating Solution

0.7 ml of SURFYNOL 420 surfactant and 30.0 g (0.02 mole) γ-CD was thenadded to the above solution and stirred while maintaining 65° C. Theheated clear solution was used to coat the HP Premium ink jet paper. Thesurface tension of the heated solution was 48-52 dyne/cm.

Coating Papers Procedure

Pre-weighed Hewlett-Packard Premium ink jet paper #51634Y was placed ona stack of 20 sheets of NEENAH BOND® paper and a draw-down bar placed atthe top of the paper. Using a Pasteur pipette, the hot additivessolutions were placed on the paper at the edge of the draw-down bar. Thedraw-down bar was then drawn-down on the paper sheet with light pressureto yield a wet film. The paper was then placed in a vacuum oven anddried under 0.1 mm Hg vacuum at 35° C. for 20 minutes. The dried paperwas re-weighed and the add-on calculated. The sheets were then useddirectly for printing.

    ______________________________________    Wire Draw Down Bar #                     Approx. Add-on %    ______________________________________     0               3-5    12               5-8    24                9-20    ______________________________________

For testing, an Atlas Ci35 weatherometer controlled irradiance exposuresystem was used which provides high intensity daylight simulation withxenon source set at an average temperature of 63° C., an irradiance of1.10 OW/m² /nm (at 420 nm), and a humidity of 30% in an industrystandard test environment (ASTM G-26 Method 3).

Color measurement was determined by an X-Rite 938 Spectrodensitometermeasurement and storage of full spectral curves. Three measurements ofeach sample with averaging were performed with automatic calculation ofCIELAB values. CIELAB calculated for D-50 standard lighting conditions.

The results are reported in the table below.

    ______________________________________                        70 h                        ΔE*                             ΔH*    ______________________________________    HP 1600 on HP Control 70     7    HP 1600 on HP with β-CD (14.0%)                          30     8    HP 1600 on HP with γ-CD (5.5%)                          30     4    HP 855 on HP Control  26     8    HP 855 on HP with β-CD                          14     4    HP 855 on HP with γ-CD (5.5%)                           9     4    ______________________________________

Additional tests yielded the following results.

    __________________________________________________________________________           15 h  30 h  70 h  115 h 200 h           ΔE*              ΔH*                 ΔE*                    ΔH*                       ΔE*                          ΔH*                             ΔE*                                ΔH*                                   ΔE*                                      ΔH*    __________________________________________________________________________    HP 1600 on           20 13 -- -- 70 7  color-                                color-                                   color-                                      color-    HP (Control)             less                                less                                   less                                      less    HP 1600 on           5  3  5  3  11 5  13 5  21 6    HP with    Additive U    with β and γ    CD)    HP 855 on           10 9  -- -- 26 8  39 8  57 8    HP (Control)    HP 855 on           4  3  4  3  4  3  6  3  10 3    HP with    Additive U    with β and γ    CD)    __________________________________________________________________________

Additional tests yielded the following results.

    ______________________________________    Accelerated Fade Study of HP 1600 on Coated Paper                    15 h     70 h                    ΔE*                         ΔH*                                 ΔE*                                        ΔH*    ______________________________________    HP Control        20     13      70    7    β-CD (9.2%)  18     13      42   10    β-CD (14.0%).sub.--                      14     11      30    8    *HMPBS (3.1%)     --     --      30   19    *HMPBS (5.1%)     --     --      33   21    *HMPBS (8.6%)     --     --      27   11    CD (5.7%)β   --     --      28   11    CD (5.7%)γ  --     --      29   16    γ-CD (5.5%) --     --      30    4    γ-CD (10%)   8      7      29    5    *HMPBS + β + γ (4.0%) (No                      --     --      37   16    precomplexation)    *HMPBS + β + γ (9.0%) (No                       5      3       7    4    precomplexation)    CD (15.0%)+ γ                      18     11      29   10    ______________________________________     () Dry addon wt.wt on the sheet     *Additive U     -- Data point not taken

Additional tests yielded the following results.

    ______________________________________    Accelerated Fade Study of HP 855 on Coated Papers                     15 h     70 h    Coating            ΔE*                              ΔH*                                      ΔE*                                           ΔH*    ______________________________________    HP control         10     9       26   8    β-CD (3.8%)   --     --      10   4    β-CD (8.7%)   7      5       14   4    β-CD (13.0%)  6      5       14   10    *HMBPS (2.8%)      --     --      14   10    *HMBPS (3.8%)      --     --      13   10    *HMBPS (4.6%)      --     --      11   9    γ-CD (5.5%)  --     --       9   4    γ-CD (10.5%) 8      6       18   6    *HMBPS + β + γ (3.0%) (No                       --     --      20   13    precomplexation)    *HMBPS + β + γ (8.1%) (No                       5      4        5   4    precomplexation)    *HMBPS + β + γ (8.1%) (repeat) (No                       --     --       4   4    precomplexation)    β + γ (15%)                       6      4       18   4    ______________________________________     () Dry addon wt.wt on the sheet     *Additive U     -- Data point not taken

The results suggest that pre-complexation of Additive U with β-CD givessuperior results than when added separately. Pre-complexation ofAdditive U with β-CD followed by mixing with γ-CD gives maximallysuperior results. Additive U when coated on HP paper withoutcyclodextrin provides some improvement. γ-CD and β-CD applied separatelyand together provides some improvement in light-fastness.

Having thus described the invention, numerous changes and modificationsthereof will be readily apparent to those having ordinary skill in theart, without departing from the spirit or scope of the invention.

What is claimed is:
 1. An ink set comprising two or more inks, whereinthe inks of the ink set possess substantially similar light fastnessproperties, wherein one ink of the ink set comprises a magenta ink. 2.The ink set of claim 1, wherein t least one of the inks contain at leastone colorant stabilizer.
 3. The ink set of claim 2, wherein the at leastone colorant stabilizer comprises a porphine.
 4. The ink set of claim 3,wherein the porphine is represented by the following formula ##STR52##wherein M is cobalt or copper; and wherein R is SO₃ H, ##STR53## COOH,or R₁ COOH wherein R₁ is an alkyl group of from 1 to 6 carbons.
 5. Theink set of claim 4, wherein the porphine isCu-meso-tetra-(4-sulfanatophenyl)-porphine orCu-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR54## or the porphine isCo-meso-tetra-(4-sulfanatophenyl)-porphine orCo-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR55##
 6. The ink set of claim 3, whereinthe at least one ink further comprises a metal or metal salt.
 7. The inkset of claim 6, wherein the metal or metal salt comprises lanthanidesand lanthanide salts, transition metals and transition metal salts, andheavy metals and heavy metal salts.
 8. The ink set of claim 6, whereinthe at least one ink further comprises one or more metalsolubility-enhancing agents.
 9. The ink set of claim 1, wherein the inkset comprises cyan, magenta and yellow inks.
 10. An ink compositioncomprising a colorant and at least one stabilizing agent, the at leastone stabilizing agent comprising a porphine.
 11. The ink composition ofclaim 10, wherein the porphine is represented by the following formula##STR56## wherein M is cobalt or copper; and wherein R is SO₃ H,##STR57## COOH, or R₁ COOH wherein R₁ is an alkyl group of from 1 to 6carbons.
 12. The ink composition of claim 11, wherein the porphine isCu-meso-tetra-(4-sulfanatophenyl)-porphine orCu-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR58## or the porphine isCo-meso-tetra-(4-sulfanatophenyl)-porphine orCo-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR59##
 13. The ink composition of claim 10,further comprising a metal or metal salt.
 14. The ink composition ofclaim 13, wherein the metal or metal salt comprises Mg, Fe, Zn,lanthanides, transition metals, heavy metals and their salts.
 15. Theink composition of claim 13, further comprising one or more metalsolubility-enhancing agents.
 16. A method of making an ink set, whereininks of the ink set possess substantially similar light fastnessproperties, the method comprising:providing an ink set comprising two ormore inks, wherein one ink of the ink set comprises a magenta ink; andadding one or more colorant stabilizers to one or more inks of the inkset.
 17. The method of claim 16, wherein the one or more colorantstabilizers comprises a porphine.
 18. The method of claim 17, whereinthe porphine is represented by the following formula ##STR60## wherein Mis cobalt or copper; and wherein R is SO₃ H, ##STR61## COOH, or R₁ COOHwherein R₁ is an alkyl group of from 1 to 6 carbons.
 19. The method ofclaim 18, wherein the porphine isCu-meso-tetra-(4-sulfanatophenyl)-porphine orCu-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR62## or the porphine isCo-meso-tetra-(4-sulfanatophenyl)-porphine orCo-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR63##
 20. The method of claim 17, whereina metal or metal salt is added to one or more inks.
 21. The method ofclaim 20, wherein the metal or metal salt comprises Mg, Fe, Zn,lanthanides, transition metals, heavy metals and their salts.
 22. Themethod of claim 17, wherein the porphine is present in an amount ofabout 0.1 to 10 weight percent porphine based on the weight of the ink.23. The method of claim 20, wherein the metal or metal salt is presentin an amount of about 0.01 to 10 weight percent metal or metal saltbased on the weight of the ink.
 24. The method of claim 20, wherein oneor more metal solubility-enhancing agents are added to one or more inks.25. A method of stabilizing a colorant comprising:adding at least onestabilizing agent to an ink composition containing the colorant, the atleast one stabilizing agent comprising a porphine.
 26. The method ofclaim 25, wherein the porphine is represented by the following formula##STR64## wherein M is cobalt or copper; and wherein R is SO₃ H,##STR65## COOH, or R₁ COOH wherein R₁ is an alkyl group of from 1 to 6carbons.
 27. The method of claim 25, further comprising adding a metalor metal salt to the ink composition.
 28. The method of claim 27,wherein the metal or metal salt comprises Mg, Fe, Zn, lanthanides,transition metals, heavy metals and their salts.
 29. The method of claim25, wherein the colorant is an ink comprising cyan, magenta, yellow orblack ink.
 30. The method of claim 27, wherein one or more metalsolubility-enhancing agents are added to the ink composition.
 31. An inkset comprising cyan, magenta and yellow inks, wherein the inks of theink set possess substantially similar light fastness properties.
 32. Theink set of claim 31, further comprising a black ink.
 33. A compositioncomprising a colorant and at least one stabilizing agent, the at leastone stabilizing agent comprising a porphine represented by the followingformula ##STR66## wherein M is cobalt or copper; and wherein R is SO₃ H,##STR67## COOH, or R₁ COOH wherein R₁ is an alkyl group of from 1 to 6carbons.
 34. The composition of claim 33, wherein the porphine isCu-meso-tetra-(4-sulfanatophenyl)-porphine orCu-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR68## or the porphine isCo-meso-tetra-(4-sulfanatophenyl)-porphine orCo-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR69##
 35. The composition of claim 33,further comprising a metal or metal salt.
 36. The composition of claim35, wherein the metal or metal salt is selected from Mg, Fe, Zn,lanthanides, transition metals, heavy metals and their salts.
 37. Amethod of making an ink set, wherein inks of the ink set possesssubstantially similar light fastness properties, the methodcomprising:providing an ink set comprising cyan, magenta and yellowinks; and adding one or more colorant stabilizers to one or more inks ofthe ink set.
 38. The method of claim 37, further comprising adding ablack ink to the ink set.
 39. A method of stabilizing a colorantcomprising:adding at least one stabilizing agent to a compositioncontaining the colorant, the at least one stabilizing agent comprising aporphine represented by the following formula ##STR70## wherein M iscobalt or copper; and wherein R is SO₃ H, ##STR71## COOH, or R₁ COOHwherein R₁ is an alkyl group of from 1 to 6 carbons.
 40. A compositioncomprising a colorant and at least two stabilizing agents, the at leasttwo stabilizing agents comprising a porphine and a metal or metal salt.41. The composition of claim 40, wherein the porphine is represented bythe following formula ##STR72## wherein M is cobalt or copper; andwherein R is SO₃ H, ##STR73## COOH, or R₁ COOH wherein R₁ is an alkylgroup of from 1 to 6 carbons.
 42. The composition of claim 41, whereinthe porphine is Cu-meso-tetra-(4-sulfanatophenyl)-porphine orCu-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR74## or the porphine isCo-meso-tetra-(4-sulfanatophenyl)-porphine orCo-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR75##
 43. The composition of claim 40,wherein the metal or metal salt is selected from Mg, Fe, Zn,lanthanides, transition metals, heavy metals and their salts.
 44. Amethod of stabilizing a colorant comprising:adding at least twostabilizing agents to a composition containing the colorant, the atleast two stabilizing agents comprising a porphine and a metal or metalsalt.
 45. The method of claim 44, wherein the porphine is represented bythe following formula ##STR76## wherein M is cobalt or copper; andwherein R is SO₃ H, ##STR77## COOH, or R₁ COOH wherein R₁ is an alkylgroup of from 1 to 6 carbons.
 46. The method of claim 45, wherein theporphine is Cu-meso-tetra-(4-sulfanatophenyl)-porphine orCu-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR78## or the porphine isCo-meso-tetra-(4-sulfanatophenyl)-porphine orCo-meso-tetra-(N-methyl-4-pyridyl)-porphine, having the followingstructures, respectively: ##STR79##
 47. The method of claim 44, whereinthe metal or metal salt is selected from Mg, Fe, Zn, lanthanides,transition metals, heavy metals and their salts.
 48. An ink-receivingsubstrate comprising a substrate having a surface and a colorantcomposition on the surface, wherein the colorant composition comprises aporphine.
 49. The substrate of claim 48, wherein the porphine isrepresented by the following formula ##STR80## wherein M is cobalt orcopper; and wherein R is SO₃ H, ##STR81## COOH, or R₁ COOH wherein R₁ isan alkyl group of from 1 to 6 carbons.
 50. A method of printing onto anink-receiving substrate comprising:providing a substrate having asurface; and applying a colorant composition onto the surface of thesubstrate, wherein the colorant composition comprises a porphine. 51.The method of claim 50, wherein the porphine is represented by thefollowing formula ##STR82## wherein M is cobalt or copper; and wherein Ris SO₃ H, ##STR83## COOH, or R₁ COOH wherein R₁ is an alkyl group offrom 1 to 6 carbons.